1
Q
what are the 5 iono and osmotic regulation categories
A
- osmoconformers
- marine elasmobranchs
- marine teleosts and chondrosteans
- freshwater fishes and elasmobranchs
- euryhaline and diadromous species
2
Q
how do osmoconformers regulate
A
- live in stable environments so dont need to regulate
- are stenohaline
- ionic concentration close to seawater (isosmotic)
- some regulation through urine and slime
3
Q
how do marine elasmobranchs regulate
A
- concentration of ions ~1/2 of SW
- osmolality slightly hyperosmotic
- increase osmolality by increasing concentration of organic solutes in the extracellular fluids (urea and TMAO)
4
Q
why dont marine elasmobranchs need to drink water
A
osmolality is slightly hyperosmotic so water diffuses into body
5
Q
how are urea concentrations maintained in marine elasmobranchs
A
- low gill permeability for this solute (phospholipid concentration)
- presence of a urea transporter for active re-uptake at gills
- special kidney tubules to reabsorb urea
6
Q
what is the function of TMAO in marine elasmobranchs
A
- increases osmolality
- counteracts the damage urea does to proteins
7
Q
how do marine elasmobranchs eliminate ions
A
- divalent ions removed in urine (urine production very low)
- Na+ and Cl- not eliminated at gills but at specialized organ called rectal gland
- ion concentration in secretion twice that of body fluids
- gills pH regulation
8
Q
how do marine teleosts and chondrosteans regulate
A
- ion concentration of plasma and ECF 1/3 of SW (hyposmotic)
- gain ions and lose water
- have to actively drink SW and use active ion transport to take up water (water follows ion movement)
9
Q
how do marine teleosts and chondrosteans get rid of ions
A
- gills and opercular epithelial tissues and sometimes skin of head have chloride cells
- efflux of Na+ and Cl- occurs here
- glomerular or aglomerular kidneys excrete divalent ions Mg2+ and SO42-
10
Q
properties of chloride cells
A
- mitochondria rich
- on gills, opercular tissue, sometimes skin of head
- basolateral membrane that is highly folded
- tubule system similar to endoplasmic reticulum
11
Q
summary of osmotic and ionic regulation in seawater teleosts
A
- water loss over gills and skin
- drink sea water
- active excretion of monovalent ions via Cl- cells on gills
- divalent ions lost in feces and urine
12
Q
how do freshwater fish and elasmobranchs regulate
A
- operate hyperosmotically
- constantly gain water osmotically and lose ions by diffusion
- lost ions replaced by food and uptake across the gills
13
Q
two types of chloride cells in freshwater teleosts
A
- alpha chloride cells
- beta chloride cells
- third type of mitochondrial rich cell now identified, thought to be a modified pavement cell
14
Q
what are alpha chloride cells
A
- found at the junction between primary and secondary lamellae
- thought to undergo differentiation when FW fish migrate to SW
15
Q
what are beta chloride cells
A
- found in the open area between secondary lamellae and sometimes on secondary lamellae especially if water is soft
16
Q
what are peanut agglutinin cells
A
- or - (move different ions)
- currently debate on which cells are which
- function in Cl- uptake/bicarbonate excretion
- function in Na+ uptake/acid excretion
17
Q
important difference between freshwater and saltwater fish regulation
A
- in freshwater fish the same cells are involved in regulating pH and ions
- FW fish have a much higher urine flow to eliminate water
- must ensure they lose as few ions as possible in urine
18
Q
how do FW fish prevent ion loss through urine
A
- glomerular filtration
- water enters proximal tubule then distal tubule
- ions are able to leave distal tubule and re enter body but water can’t follow bc its impermeable
- water goes to bladder
19
Q
how do euryhaline fish regulate
A
- live in estuarine and intertidal environments
- have ability to cover over their CC with pavement cells to minimize ion loss in hypotonic mediums
- hormone prolactin plays a role in minimizing Na+ loss when salinity drops
20
Q
what are diadromous fish and the types
A
- spend part of their life cycle in FW and part in SW
- catadromous: live primarily in FW but migrate to SW to breed
- anadromous: migrate from SW to breed in FW
21
Q
how do catadromous species regulate
A
- hormone cortisol upregulates mechanisms that allow adults to survive in a hypertonic environment
- increase in gill chloride cell density, size, and Na+K+ATPase activity
- enhanced capacity to take up ions across the gut to allow water uptake
- increased permeability of the urinary bladder for water retention
22
Q
how do anadromous species regulate
A
- adult salmon get a decrease in Na+K+ATPase activity and a change in isoform from alpha1a to alpha1b
- young salmon must return to the sea and transform from a parr to a smolt
- hormones in smoltification process: thyroxine, cortisol, growth hormone
23
Q
gill functions
A
- ionic regulation
- pH regulation
- nitrogen excretion
- gas exchange
- in most fish nitrogen excreted in form of ammonia
24
Q
how is nitrogen excreted across the gills
A
- form of ammonia as a consequence of protein metabolism
- rapidly diffuses because cell membranes in gills are permeable to ammonia gas
- to maintain gradient for diffusion NH3 is protonated to form NH4+
25
how is the vertebrate nervous system divided
- central nervous system: brain and spinal cord
- peripheral nervous system: afferent/sensory nerve tracts, motor/efferent nerve tracts, autonomic nervous system
26
three regions of the brain
- prosencephalon (forebrain)
- mesencephalon (midbrain)
- rhombencephalon (hindbrain)
27
3 main parts of prosencephalon
- olfactory bulbs
- olfactory lobes (telencephalon)
- diencephalon
28
olfactory bulbs
primary olfactory centres
29
olfactory lobes
- integrate/process olfactory information
- cerebrum: decision making
30
diencephalon regions
- epithalamus
- thalamus
- hypothalamus
31
epithalamus
- has nervous connections with the pineal gland
- receives sensory inputs from the olfactory region and telencephalon
32
hypothalamus
- major integratory system of the brain
- controls pituitary function
- major link between nervous and endocrine systems
33
optic lobe (tectum)
- centre for the integration of visual inputs and other sensory information
- memory/learning
34
cerebellum
- integrates sensory information and coordinates
- posture, swimming/movements, balance
- most variable brain region
35
medulla oblongata
- contains nerve fibres from all regions of the cns
- receives sensory inputs/transmits efferent motor impulses
- closely associated with nerves carrying info to and from skin, lateral line, gustary system, and viscera
36
PNS cranial nerves
0 - terminal
I - olfactory
II - optic
III - oculomotor
IV - trochlear
VI - abducens
V - trigemial
VII - facial
VIII - auditory
IX - glossopharyngeal
X - vagus
37
types of facial nerves
- superficial
- ophthalmic
- deep
- maxillary
- mandibular
- hyomandibular
38
0) terminal nerve fibre type
sensory
39
I) olfactory nerve fibre type
sensory
40
II) optic nerve fibre type
sensory
41
III) oculomotor nerve fibre type
sensory and motor
42
IV) trochlear nerve fibre type
sensory and motor
43
VI) abducens nerve fibre type
sensory and motor
44
V) trigeminal nerve fibre type
sensory
45
VII) facial nerve fibre type
sensory and motor
46
VIII) auditory nerve fibre type
sensory
47
IX) glossopharyngeal nerve fibre type
sensory and motor
48
X) vagus nerve fibre type
sensory and motor
49
spinal cord
- continuous with the medulla oblangata
- extends down the vertebral column
- has a central canal with grey matter composed of unmyelinated nerve fibres
50
where do paired spinal nerves arise from
grey matter along the length of the spinal cord
51
purpose of dorsal branches/roots in spinal cord
carry somatic and visceral afferent (sensory) fibres and some visceral efferent fibres
52
purpose of ventral branches
- carry somatic (motor) nerves and visceral efferent nerve fibres contributing to the autonomic nervous system
53
what is the autonomic nervous system composed of
- sympathetic and parasympathetic components
- involved in the control of smooth muscle, heart, and certain glands
54
types of nerves in the ANS
- pre-ganglionic and post-ganglionic nerves
- final neurotransmitter released can be acetylcholine (parasympathetic) or catecholamines noradrenaline or adrenaline (sympathetic)
- role often antagonistic
55
what are hormones
chemical compounds released by one tissue that travel in the blood stream before stimulating other tissues
56
what is autocrine
compound chemical released by a cell which influences that cell's physiology
57
what is paracrine
compound chemical released by a cell which influences adjacent cell's physiology
58
what is endocrine
compound chemical released by a cell which influences physiology of cells in other organs/tissues ie hormones
59
what is the pineal gland
- located on dorsal surface of diencephalon
- sensory function: photosensitive
- secretes melatonin (circadian rhythm)
60
importance of melatonin
- provides the link between photoperiod and hypothalamic-pituitary function and between photoperiod and seasonal gonadal development
61
what is the pituitary gland
- under hypothalamus
- controls secretory activity of other endocrine glands
- produces hormones that stimulate target tissues
- most complex endocrine organ
- primary link between nervous and endocrine systems
- controlled by hypothalamus
62
parts of the pituitary gland
- neurohypophysis (Pars Nervosa)
- adenohypophysis
63
parts of adenohypophysis
- pars intermedia
- pars distalis
64
parts of pars distralis
- rostral
- distal
65
difference between adenohypophysis and neurohypophysis
- adeno: produce and release hormones when stimulated by hormones from hypothalamus
- neuro: don't produce its own hormones but releases ones from the hypothalamus
66
hormones released from the hypothalamus
- CRH: corticotropin releasing hormone
- AVT: arginine vasotocin
- TRH: thyrotropin releasing hormone
- GnRH: gonadotropin releasing hormone
- GHRH: growth hormone releasing hormone
- GHIH: growth hormone inhibitory hormone (somatostatin)
- PRH: prolactin releasing hormone
67
hormones released from the neurophypophisis (pars nervosa)
- MCH: melanin concentrating hormone
- AVT: arginine vasotocin
- isotocin (analogous to oxytocin)
68
hormones released from the adenohypophysis
- ACTH: adrenocorticotropic hormone
- TSH: thyroid stimulation hormone (thyrotopin)
- GTH: gonadotropins I and II (FSH and LH)
- GH: growth hormone
- PRL: prolactin
- SL: somatolactin
- MSH: melanophore stimulating hormone
69
hormones released by pars distalis
- ACTH: adrenocorticotropic hormone
- TSH: thyroid stimulation hormone
- GTH: gonadotropins I and II
- GH: growth hormone
- PRL: prolactin
70
hormones released by pars intermedia
- SL: somatolactin
- MSH: melanophore stimulating hormone
71
why doesn't the pars nervosa make its own hormones
- it is where nerves from the hypothalamus terminate
- hormones isotocin, arginine vasotocin, and melanin concentrating hormone are released from hypothalamus then enter hypophyseal artery then circulation
72
purpose of isotocin
- reproductive
- renal
- cardiovascular
- metabolic
- hydroosmotic
73
purpose of arginine vasotocin
- salt and water balance
- mediates renal water retention
- promotes gill Na and Cl extrusion
- constrictor of vascular and other smooth muscles
74
purpose of melanin concentrating hormone
- concentrates melanin granules in melanophores
- lightens body colour
75
purpose of melanophore stimulating hormone
- acts on melanophores to cause pigment dispersal
- fish gets darker
- stimulates melanin production
75
antagonistic melanin hormones
melanin concentrating hormone and melanophore stimulating hormone
76
purpose of somatolactin
- maturation/reproduction
- acid-base balance
- control of ion levels
77
how does the pars distalis release hormones
- produces 6 hormones in response to release of hormones from hypothalamus
- trigger hormones arrive mainly through portal circulation
- most hormones have effects on other endocrine organs - only prolactin has direct effects
77
purposes of prolactin
- released in response to prolactin releasing hormone from hypothalamus
- wide range of actions such as lipid metabolism and gonadal steroidogenesis
- main role is regulation of water and ion permeability of gills, kidney, and bladder
- decrease in permeability of water, increase ion uptake across gills
78
anatagonistic hormones regarding ion regulation
prolactin and arginine vasotocin
78
hormones that work together to regulate Ca
prolactin and somatolactin
79
thyroid
a diffuse gland scattered around blood vessels in the region ventral to the pharynx
79
functional unit of the thyroid gland
- follicle
- single layer of epithelial cells that enclose a fluid filled space (colloid)
80
what do thyroid cells do
- take up iodide and synthesize T3 (tri-iodothyrosine) and T4 (thyroxine) from amino acid tyrosine
- T4 prominent hormone produced
- both stored prior to release
81
how are T3 and T4 released
- released in colloid bound to glycoprotein thyroglobulin
- secretion and release controlled by TSH (thyrotropin) which is controlled by TRH from the hypothalamus
82
T4 and T3 function
- T4 is main hormone in circulation
- T4 converted to active form (T3) in peripheral tissues
- growth and development
- metamorphosis
- osmoregulation
- metabolism?
83
where are interrenal cells located
in the head kidney in close association with veins
84
main hormones produced by interrenal cells
- teleosts: cortisol, some cortisone and corticosterone
- elasmobranchs: 1alpha-hydroxycorticosterone
85
how does production of cortisol work
- not stored
- synthesized when interrenal cells are stimulated by ACTH which is controlled by CRH
86
characteristics of cortisol
- member of the steroid family
- synthesized from cholesterol
- released in response to stress
- primary effects mediated by changes in gene expression
87
purposes of cortisol
- mineralocorticoid (Na/Cl regulation, chloride cell proliferation)
- mobilization of energy stores (glucose, FFA, protein)
88
consequences of cortisol
- immunosuppression
- decreased growth
- impaired reproduction
89
where are catecholamines produced
- chomaffin tissue
- located in head kidney
90
what are catecholamines
- adrenaline and noradrenaline synthesized from the amino acid tyrosine
- stored prior to release
91
purpose of catecholamines
- fight or flight response
- released directly into circulation in response to cholinergic parasympathetic nervous stimulation
92
how do catecholamines work
- bind to receptors on cell surface
- mediate short-term effects aimed at increasing circulating energy substrates and blood oxygen delivery
- rapidly cleared from blood due to costs
93
effects of catecholamines
- increased ventilation and gill perfusion
- stimulation of Na/H exchange on red blood cells
- release of erthyrocytes from spleen
- increased heart rate and strength of contraction
- increase Ca entry
- increase in blood pressure, vasoconstriction
- release of glucose and fatty acids, increases energy substrates
94
what is the caudal neurosecretory system
- exclusive to fish
- located in posterior segment of spinal cord
- composed of enlarged neurosecretory cells (Dahlgren cells) that originate in the spinal cord and have swollen nerve terminals that terminate in the urophysis
- urophysis composed of axons and nerve terminal of Dahlgren cells and a network of blood vessels that receive hormones produced
95
peptide hormones produced in caudal neurosecretory system
- urotensin I
- urotensin II
96
purpose of urotensin I
- involved in stress responses
- vasorelaxation
- osmoregulation
97
purpose of urotensin II
- stimulates the smooth muscle of the reproductive tracts
- Na exchange
98
main hormones involved in calcium homeostasis
- stanniocalcin
- calcitonin
99
properties of stanniocalcin
- glycopeptide
- produced in corpuscles of stannius (spherical bodies on or in kidney)
- inhibits active uptake of calcium across gills
- inhibits intestinal calcium absorption and promotes accumulation of Ca in bones and scales
100
properties of calcitonin
- peptide
- produced by ultimobranchial gland (ventral to esophagus)
- minor regulator of Ca levels
- inhibits gill Ca influx
stimulates osteoblast development (bone growth)
101
properties of stanniocalcin and calcitonin
- hypocalcaemic
- antagonistic to effects of prolactin and somatolactin
102
how is fish blood volume controlled
- renin-angiotensin system
- natriurectic peptides
103
what is the renin-angiotensin system
- activated by hypotension, hypovolemia, and osmotic pertubations
- involved in maintenance of ion and fluid balance
104
renin-angiotensin system hormones
- angiotensinogen
- renin (enzyme)
- ACE (angiotensin converting enzyme
105
where is angiotensinogen produced
liver
106
where is renin produced
- kidney tissue
- corpuscles of stannius
- rectal gland of elasmobranchs
107
where is ACE (angiotension converting enzyme) produced
- gill
- kidney
- number of other tissues
108
renin-angiotensin system process
- angiotensinogen produced in liver
- renin converts angiotensinogen to angiotensin I
- ACE converts angiotensin I to angiotensin II
- angiotensinase deactivates angiotensin II to angiotensin III
109
actions of angiotensin II
- increase in blood pressure
- increase in drinking
- changes in renal function
- overall increase in blood volume
110
what are natriurectic peptides antagonistic to
angiotensin II
111
what are the natriurectic peptides
- ANP
- CNP
- VNP
112
where are natriurectic peptides produced
chambers of the heart in response to stretch
113
effects of natriurectic peptides
- decreased drinking and drinking-coupled salt uptake by gut
- increase extrusion of excess salt at gills and rectal gland
- relaxation of smooth muscle, decrease in blood pressure
- overall decrease in blood volume
114
pancreas
- exocrine and endocrine
- in some fish large lumps of endocrine pancreatic tissue (brockman bodies) are present
- in other species endocrine pancreas is more diffuse and scattered around the gall bladder, pyloric caecae, and foregut
115
hormones produced by pancreas
- all peptides
- insulin
- glucagon
- somatostatin
116
properties of insulin
- produced by B cells
- promotes glucose uptake by tissues
- gluconeogenesis
- fatty acid uptake by liver and lipogenesis
- anabolic - building
117
properties of glucagon
- produced by A cells
- largely oppose insulin actions
- glycogenolysis
- lipolysis
- catabolic - breaking down
118
properties of somatostatin
- produced by D cells
- inhibits release of glucagon and insulin
- promotes lipolysis and hyperglycemia
119
which pancreas hormones are antagonistic
insulin and glucagon, somatostatin and insulin
120
purpose of polypeptides released from the gut
- control digestive processes
- enzyme secretion
- GI motility
- appetite control
121
hormones released by the gut
- ghrelin
- secretin
- gastrin
- CCK
122
properties of ghrelin
- produced by stomach
- stimulates GH release
- stimulates appetite
123
properties of secretin
- secreted by stomach
- stimulates pancreatic HCO3 secretion into intestine --> raises pH of intestines to receive acidic food
124
properties of gastrin
- synthesized by stomach epithelium
- stimulates gastric gland secretions and gastric motility
125
properties of CCK
- synthesized by intestinal epithelium
- stimulates pancreatic enzyme secretion and gall bladder contraction (lipid digestion)
- decreases appetite
126
why is growth well studied
- good indicator of the health of individuals and populations
- needed metric in aquaculture and fisheries modelling/management
127
growth characteristics
- net result of anabolic and catabolic processes occurring in an organism over time
- determinate in mammals and birds
- indeterminate in most fish
- fish growth determined by genetic potential
- doesnt happen at a constant rate
- a change in length, or mass, over time
128
common equation for calculating growth
SGR (%BM/day) = 100(ln final mass - ln initial mass) / days
129
von bertalanaffy equation
Lt = Lmax (1-e^kt)
- Lt = length at point in time
- Lmax = max length attained by a species
- e = base of natural logarithms
- t = point in time
- k = growth rate coefficient
130
methods to determine growth rates/age
- mark/recapture
- back calculation from rings on hard structures
131
how is growth calculated from rings on hard structures
deposition of minerals as fish grows leaves growth rings
132
structures used to calculate growth
- scales
- otoliths
- spines
- vertebrae
133
how are scales used to determine growth
- fibroblast cells in the fibrillar plate region deposit collagen (protein) and CaCO3 (calcification)
- circuli
- due to faster growth in summer than winter circuli become closer to each other during winter forming an annulus
- age determined by counting annuli
134
what are circuli
growth ridges on scales that form at a constant rate
135
what is an annulus
cluster of dense circuli on scales
136
how is age determined in cartilaginous fish
- centrum of vertebrae in some sharks
- spines (dorsal or pectoral fin) can be used
137
how are otoliths used for aging
- small bones located in inner ear of bony fishes
- can be sectioned/polished
138
methods to determine instantaneous growth rates
- RNA:DNA ratio
- phenylalanine flooding dose method
139
what is RNA:DNA ratio
- determines instantaneous growth rate
- dna content is constant but rna content is a function of a fish's protein synthesis rate
140
what is phenylalanine flooding dose method
- determines instantaneous growth rate
- inject fish with an excess of the 3H-phenylalanine and measure the incorporation of this radiolabel into muscle, other tissues, etc
141
what is growth rate dependent on
- fish's energetic budget
142
growth rate based on energetic budget equation
Gs + Gr = C - [(Mr + Ma + SDA) + (F + U)]
- C = rate of energy consumption
- Mr = standard metabolic rate
- Ma = metabolic rate increase due to activity
- SDA = metabolic rate increase due to specific dynamic action
- F + U = waste losses due to feces and urine rates
- Gs = somatic growth rate due to protein synthesis and lipid deposition
- Gr = growth rate due to gonad synthesis
143
other factos that affect growth rate
- temperature
- hypoxia
- photoperiod/season
- compensatory growth
144
what is compensatory growth
a phase of accelerated growth when favourable conditions are restored
145
hormones that regulate growth
- IGF-1: insulin-like growth factor 1
- GH: growth hormone
- GHRH: growth hormone releasing hormone
- GHIH: growth hormone inhibitory hormone (somatostatin)
146
what is myostatin
- polypeptide produced primarily by skeletal muscle cells that circulates in the blood and inhibits muscle growth
- ensures muscles do not get too large
147
how is growth regulated in the hypothalamic-pituitary-growth axis
- environmental stimuli, stress, and endogenous rhythms stimulate cns
- cns releases neurotransmitters to hypothalamus
- hypothalamus releases GHRH
- GHRH triggers release of GH from pituitary
- GH triggers IGF-1 to release to target tissues
- buildup of IGF-1 and GH detected by liver makes negative feedback loop to release somatostatin and slow growth
148
5 distinct periods of fish life history
- embryonic period
- larval period
- juvenile period
- adult period
- senescence
149
what is the embryonic period
- developing fish dependent on nutrition from the mother
- yolk, placenta connection, maternal secretions
150
what is the larval period
- begins with ability to capture food
- ends with development of axial skeleton, fins, and organ systems
151
what is the juvenile period
- begins when fins and organ systems are fully formed
- change from larvae to juvenile may be metamorphosis
152
what is the adult period
- begins when fish is reproductively mature
153
what is senescence
- period when growth has mostly stopped
- gonads are degenerate and incapable of producing gametes
154
phases of the embryonic period
- fertilization
- cleavage - egg phase
- embryo phase
- free embryo
155
what happens during fertilization
- sperm penetrates the egg
- chorion stiffens due to process called water hardening
- protects fragile embryo
156
what happens in cleavage-egg phase
- 1st cell until appearance of neural plate
157
what happens in embryo phase
major organs appear until hatching
158
what happens in free embryo phase
starts with hatching and ends when all yolk is absorbed and fish starts feeding
159
types of eggs
- pelagic
- benthic
- glutinous
160
what are pelagic eggs
- neutrally buoyant due to oil globulet
- develop in the water column
161
what are benthic eggs
laid by the female on the bottom
162
what are glutinous eggs
attached to hard substrates on/attached to the bottom
163
characteristics of the larval period
- begins at exogenous feeding, ends when formation of skeleton and organs are complete and median fin fold is gone
- typically transparent
- some have spines for protection
- eyes may be oddly shaped or on stalks
- many aid in buoyancy through high surface area, oil globules, watery tissues
- predation is heavy
164
what is direct development
- at the start of exogenous feeding the fish is a miniature version of the adult
- no larval stage
- ex. sculpins
165
characteristics of the juvenile period
- begins when organ systems and fins fully formed
- ends when sexually mature
- miniature adult
- rapid growth period
166
types of feeding habits
- detritivore
- herbivore
- carnivore
- omnivore
167
detritivore
consume freshly dead or partially decomposed organ material
168
herbivore
eat plant-based material
169
carnivore
feeding on other animals
170
types of carnivores
- macrocarnivores
- microcarnivores
- parasites
171
macrocarnivores
piscovorous fish and those that feed on crustaceans
172
microcarnivores
feed on zooplankton, fish eggs
173
parasites
feed on other fish without killing them
174
omnivore
consume a variety of food types, usually opportunistic
175
types of fish diets
- europhagous: mixed diet
- stenophagous: limited number of food sources
- monophagous: only one food source
176
types of prey capture methods
- oral manipulators
- ram feeders
- suction feeders
177
oral manipulator feeders
- use teeth to eat
- scraping, biting, gripping, grasping
178
ram feeders
- take food with open mouth ramming food through mouth
- continuous swimmers that strain food
179
suction feeders
- fish is stationary and creates inward directed water current by expansion of buccal cavity
- often combined with protrusible jaws
180
types of mouth structures
- ancestral (plesiomorphic)
- advanced (apomorphic)
181
ancestral (plesiomorphic) mouth structure
- firm jaws and sharp teeth
- immobile premaxilla and mobile maxilla
182
advanced (apomorphic) jaw type
- mobile premaxilla and mobile maxilla
- premaxilla can swing ventrally and protrude
183
advantages of advanced jaw type
- large gape relative to jaw size
- suction volume increased
184
why can sharks protrude their jaws
upper jaw not fused to cranium
185
where are teeth located in fish
- on jaws
- on lower part of mouth
- on tongue
- on palate
- pharyngeal teeth
186
8 types of teeth
- canine
- villiform
- molariform
- cardiform
- incisor
- fused into beaks
- flattened triangular cutting teeth
- pharyngeal teeth
187
canine teeth
conical teeth found at the corners of the mouth
188
villiform teeth
generally small fine teeth but can become elongate
189
molariform teeth
pavement-like cursing teeth, can be individual or form plates
190
cardiform teeth
very fine pointed teeth
191
incisor teeth
large teeth with flattened cutting surfaces for feeding on molluscs and crustaceans
192
beak teeth
used for scraping algaae off corals
193
flatted triangular cutting teeth
often serrated to aid in cutting action
194
pharyngeal teeth
assist in holding prey and in many species have structural modifications for crushing, grinding, tearing
195
what are gill rakers
inwardly directed bony or cartilaginous projections from gills
196
gill rakers in piscivores
- short and stubby
- prevent prey from escaping
- descale prey
- protect gill filaments
197
gill rakers in filter feeders
- long and thin
- closely spaced
- paddlefish, basking shark
198
basking shark gill rakers
shed every autumn and regrow in spring
199
palatal organ (pharyngeal pad)
- thick muscular pad on roof of pharynx in cyprinids
- involved in the selective retention of food particles inside the oropharyngeal cavity
200
epibranchial organ
- a paired dorsal diverticulum at the posterior limit of the pharynx in certain microphagous fishes
- in all forms prominent gill rakers extend into the organ
- small food particles get trapped
201
differences in digestive tract morphology depending on diet
- structure of mouth and teeth, gill rakers, pharynx, stomach, and length of intestine
- carnivorous fish: definite stomach (foregut)
- herbivorous fish: no stomach, extended midgut area
202
relative gut length
- relative gut length RGL = gut / body length
- high RGL = species consuming detritus, algae
203
stomach characteristics
- produces hydrochloric acid
- when stomach distends parasympathetic nervous stimulation of gastric glands which produce HCl and pepsinogen
- low pH converts inactive pepsinogen to active pepsin
- other enzymes secreted work on lipids, carbohydrates, and chitin
- if no stomach HCl or pepsin is formed in the gut
204
which cells produce HCl
parietal cells
205
which cells produce pepsinogen
chief cells
206
where is bile produced
liver
207
pancreas characteristics
- produces HCO3 which raises gut pH
- produces many digestive enzymes stored in inactive forms (zymogens)
208
process when food enters pancreas
- food in the gut
- activation
- proteases produced by intestine
- converts trypsinogen into trypsin
- activates pancreas enzymes
209
zymogens made by the pancreas
- proteases: protein breakdown
- amylases: starch breakdown
- chitinases: chitin breakdown
- lipases/co-lipases/phospholipases: lipid breakdown
210
gall bladder
- stores bile
- emulsification to allow digestion by lipases and esterases
- neutralizes HCl from stomach
- maintains alkalinity of the gut pH
211
intestine
- surface epithelial cells can produce a variety on enzymes that act on carbs and peptides
212
enzymes produced by intestine epithelial cells to act on carbs
- B = insulin
- A = glucagon
- D = somatolactin
213
what is specific dynamic action
increase in metabolic rate following the ingestion of a meal
214
specific dynamic action
- integrates the sum of all energy expenditures involved in feeding
- includes a muscular mechanical component and the endogenous post-absorption of nutrients and digestion
215
why is there a major influence on oxygen consumption with specific dynamic action
- energy requirements of biochemical transformation of food
- protein synthesis occurring in post-absorptive stage
216
how does oxygen consumption change during specific dynamic action
- immediate spike in O2 consumption rate then slowly returns to normal
- spike smaller and return to baseline faster for small meals
- when in a hypoxic environment initial spike is smaller but it takes longer to return to baseline
217
main fish mating systems
- semelparity
- iteroparity
- promiscuous reproduction (broadcast spawning)
- polygamy
- polygyny
- polyandry
- monogamy
218
semelparity
only reproduce once
219
iteroparity
individuals spawn two to several times in their life
220
promiscuous reproduction (broadcast spawning)
- no obvious mate choice occurs
- large groups/multiple partners
- big mating aggregations
221
polygamy
one sex has multiple partners
222
polygyny
a few males get multiple female mates
223
polyandry
one female mates with several males
224
monogamy
fish live in pairs and stay together and mate
225
alternative reproductive strategies
- sneaking in
- hermaphrodites
- all female reproduction
226
sneaking reproductive strategies
- jack males: small precocious males that sneak in to breed with females
- satellite males: resemble females and sneak in to fertilize eggs
227
forms of hermaphroditism
- synchronous
- sequential (protandrous and protogynous)
228
synchronous hermaphroditism
- capable of releasing viable eggs and sperm in the same spawning
- least common
- when there are limited opportunities or time for spawning
229
sequential hermaphroditism
- change sex over their life history
- protandrous: males first then change to females
- protogynous: females first
230
types of all female reproduction
- gynogenetic females (parthogenesis)
- hybridogenetic females
231
gynogenetic females
- females are 3N and so are eggs (no meiosis)
- sperm from males not required for fertilization
- only required to activate cell division
- only clones produced
232
hybridogenetic females
- diploid
- all female haploid eggs
- paternal genes discarded at meiosis during gamete production
- eggs fertilized by another species by only females produced
- male contribution lost after one generation
233
types of reproductive guilds
- non-guarders
- guarders
- bearers
234
types of non-guarders
- open substrate spawners
- pelagic spawners
- benthic spawners
- brood hiders
235
types of guarders
- substrate choosers: no nest construction
- nest spawners: cavity, plant material, bubbles
236
oviparous
produce eggs that hatch outside the body
237
types of bearers
- external (still oviparous): mouth, skin, forehead brooder
- internal (produce live young): internal fertilization, requires intromittent organ to deposit sperm
238
types of internal bearers
- ovoviviparous: internal growth and fertilization but no additional nourishment from mother
- viviparous: maternal nourishment
239
adpatations of viviparity
- trophotaeniae
- trophonemata
- intrauterine cannabilism or oophagy
- placental viviparity
240
trophotaniae (goodeids)
fetal processes from gut or anus that increase absorbing surface and enhance absorption of nutrients from ovary
241
trophonemata (rays)
- tufts of uterine epithelium that enter embryo through spiracle and pass into esophagus
- nutrients secreted enter gut of embryos
242
placental viviparity (requiem sharks and hammerhead sharks)
- yolk sac placenta
- temporary association with maternal tissue
- appendiculae: vascular ridges that develop on yolk stalk and take up uterine milk
243
sexual dimorphism traits
- size
- breeding tubercles/contact organs
- intromittent organs
- dichromatism (colour differences)
- some differences only at spawning
244
fish testes
- usually paired and suspended in anterior body cavity by mesentaries called mesorchia
- smooth, white, up to 12% of BW
245
male reproductive organs in chondrichthyes
- sperm travel through tubules before being released into urogenital sinus or stored in sperm sac
- sperm delivered to female through groove in claspers
- Leydig's gland: modified cells in the anterior kidney that secrete seminal fluid into the epididymus
246
male reproductive organs in teleosts
- in most groups no connection between reproductive and urinary systems
- sperm move down sperm ducts and exit through a genital pore
- in some species sperm and urine enter into a common urogenital sinus
- in some species sperm are released into the body cavity and exit through a genital pore
247
fish ovaries
- suspended by mesovarium
- usually paired
- large yellow organs, 30-70% BW
248
female reproductive organs in chondrichthyes
- eggs released into body cavity (gymnovarian condition)
- enter the oviducts through a funnel (ostium) located anterior to the ovaries
- reach shell gland where fertilization occurs
- horny shell (oviparous) or membrane (viviparous) is secreted
- posterior portion of oviduct can be enlarged to serve as a uterus
249
female reproductive organs in non-teleost osteichthyes
- gymnovarian condition
- eggs released into body cavity
- enter oviduct through funnel
250
female reproductive organs in teleosts
- oviducts continuous with outer tissue layers of the ovaries (cystovarian condition)
- eggs exit through genital pore located between anus and urinary pore
251
factors that control reproduction
- photoperiod
- temperature
- hypothalamic-pituitary-gonad axis
252
brain/hypothalamus control of reproduction
GnRH gonadotropin releasing hormone
253
pituitary gland control of reproduction
- gonadotropins: GtH (FSH and LH)
- stimulate gonadal development and secretion of steroids
254
gonad control of reproduction
gonadal steroid hormones
255
gonadal steroid hormones
- estrogen/estrodiol: stimulates production of vitellogenin
- progestin: stimulated by LH - oocyte maturation
- androgens: secondary sexual characters, behaviour
256
where are sperm produced
- seminiferous tubules in bony fish
- spermatic ampullae (cavities) in sharks and agnathans
257
how do sperm cells develop
- develop in association with Sertoli cells whose function is stimulated by FSH (follicle stimulating hormone)
- Leydig cells produce androgenic steroid hormones after being stimulated by leutenizing hormone (LH)
258
steps of sperm production
- spermatogonium (2n) undergoes mitoses to become spermatocytes (2n)
- spermatocytes undergo meioses to become spermatids (1n)
- spermatids undergo differentiation to become spermatozoans (1n)
259
oogenesis
the process by which primordial germ cells produce oocytes that become ready to be fertilized eggs
260
6 stages of oocyte development
- oogonia proliferation
- chromatin nucleolus stage
- primary growth
- secondary growth
- oocyte maturation
- ovulation
261
oogonia proliferation stage
- stem cells in the germinal epithelium undergo mitoic division
- frequently form nest cells
- oogonia are surrounded by pre-follicle cells
262
chromatin nucleolus stage
- meiosis I starts
- follicle still not completely formed
- nucleoli can be seen on periphery of the nucleus
- process of meiosis arrested prior to completion
- oocyte still within germinal epithelium
263
primary growth stage of oocyte development
- oocyte covered by a full layer of follicular cells
- has one to many nucleoli (PGon and PGpn)
- oocyte contains balbiani bodies, cortical alveoli (food for embryo), and oil droplets
- zona pellucida develops between ooxyte and follicular cells
264
secondary growth stage (vitellogenesis)
- stimulated by estrogen
- uptake of vitellogenin (complex glycophospholipoprotein produced by liver) by the oocyte
- vitellogenin transformed into lipoprotein and protein yolk stored in yolk globules
- further accumulation of oil droplets
- oocyte increases dramatically in size
265
oocyte maturation
- morphological and physiological changes to oocyte
- nucleus takes an eccentric position, migrates to periphery and breaks down - first meiotic division is completed
- egg gets bigger due to hydration of egg
- oil droplets fuse to become oil globules and eventually form one oil globule in marine eggs
- meiosis I is completed
- cells arrest at metaphase of 2nd meiotic division
266
ovulation
- shared basement membrane, follicle cells, and overlying germinal epithelium break
- creates opening through which oocyte moves into ovary lumen
- post-ovulatory follicle complex is left
267
what happens in ovulation doesn't occur
- oocytes undergo atresia
- process of degeneration and removal of oocytes from the ovary
- nutrients may be reabsorbed
268
differences in fish eyes compared to mammals
- lens is round and cannot change shape
- eyes generally positioned laterally but protrudes and eyes bulge
- very few fish with eyelids but have other structures to protect the eye
- pupil is usually round or elliptical and can't change size
- many structural adaptations
- some fish have vestigial eyes
269
how fish lens work
- generally round and cannot change shape
- some elasmobranchs have elliptical lens
- focus achieved by moving position of lens not changing shape
- very high refractive index = light bending ability
270
fish eye position
- laterally (side of head)
- lens protrudes through pupilar opening in the iris
- eye bulges from the body
- large field of view to almost behind animal
- binocular vision in front
271
protective eye structures
- cornea has 4 layers to protect the lens
- spectacle for fish that live on sandy/silty bottoms
- sharks have nictitating membrane and roll eye into sockets
- some rays have eye-flap pupillary operculum - not protective but increases sensitivity to movement in the visual field
272
fish pupil
- mostly round or elliptical
- fixed (cannot change size)
- in many elasmobranchs it can be a slit or crescent shape and can change in size
273
eye structural adaptations
- positioned forward
- directed upward
- on short stalks
- divided into aerial and aquatic vision
274
parts of the anterior eye
- cornea
- iris
- lens
275
cornea
- made of 4 tissue layers and normally clear
- can have some patches of changeable colouration to eliminate short wavelength light
- sclera clear in area of cornea
276
sclera
- aka sclerotic coat
- tough connective tissue layer that goes around the entire eye
- can be strengthened by scleral ossicles or cartilage
277
iris
- elipsoid in most fish
- usually incapable of movement for light regulation
- some have contractile irises
- pupil: gap in the iris
278
lens
- generally round and cannot change shape
- composed of 50% protein and usually clear but can have some colour
- muscle attached to bottom of eye moves lens to focus
279
how do fish focus eyes
- muscle attached to bottom layer of eye contracts/relaxes
- moves lens closer or further away from retina
280
difference in teleost and elasmobranch focusing
- teleosts: retractor muscle pulls lens inward towards retina
- elsamobranchs: protractor muscle pulls lens outward
281
parts of the posterior eye
- sclera
- argentea (stratum argenteum)
- choroid
- tapetum lucidum
- retina
282
argentea (stratum argenteum)
- stops light from entering the eye through its walls
- important for fish with transluscent tissues around eye
283
choroid
- highly vascularized region between sclera and retina
- supplies blood to retina (highly metabolic tissue)
- enhances visual sensitivity under low light conditions
- expanded in back of eye to form choroid body or gland associated with a rete mirable since metabolically active eye needs blood with a lot of ATP
284
tapetum lucidum
- highly reflective layer of choroid or retina
- guanine crystals reflect light that has passed through visual cells back to system
- adaptation for dim light conditions
- pigment cells can migrate forward to reduce reflectivity
285
retina
- light sensitive part of the eye
- photoreceptors that contain pigments that absorb light (rods and cones)
- functions over range of light intensity
- accommodation to light intensity by structural changes
- pigmental absorption of light stimulates rods/cones to send electrical impulses to the optic nerve
286
rods vs cones
- rods: only detect light intensity, black and white vision, low light
- cones: bright light, colour vision, three types with different colour reception
287
structural changes in retina to accommodate light intensity
- retinomotor migration of rods, cones, and melanin granules in pigment epithelium
- takes about 30 minutes
288
olfaction process
- stimulation of sensory receptors in olfactory organ
- olfactory nerve I
- olfactory bulb
289
olfactory organs
- found in sacs or pits connected to external surface by nares/nostrils
- anterior portion of head
- usually bilateral
- has incurrent and excurrent nares for water to flow through
- pits/sacs lined with olfactory epithelium with olfactory receptors
- folding of olfactory epithelium forms olfactory rosette
290
olfactory epithelium
- ciliated non-receptor cells, receptor cells, supporting cells, and mucous cells
- ciliated cells move water
- olfactory sensitivity related to area of olfactory epithelium and density of receptor cells
291
olfactory receptor cells
- olfactory receptor neurons
two types: ciliated and microvillis
- odorants bind to receptors on microvilli and cilia
- send a slender cylindrical dendrite toward the surface of the epithelium
- directly connected with the olfactory bulb by its axon
292
taste
detects dilute solutions by contact mostly for food detection
293
location of taste
- cutaneous taste buds on exterior surfaces innervated by facial nerve VII
- internal taste buds innervated by glossopharyngeal IX and vagus X nerve
294
acusticolateralis system
- senses sounds, vibrations, and other displacements of water
- involved in hearing, equilibrium, balance, and orientation in 3d space
- includes inner ear, swim bladder, lateral-line mechanoreceptors
295
parts of the inner ear
- dorsal part (pars superior)
- ventral part (pars inferior)
296
dorsal part of the ear (pars superior)
- 3 semi-circular canal oriented in vertical, horizontal, and lateral planes
- ultricus with small otolith (ear stone)
- functions in equilibrium and balance
297
ventral part of the ear (pars inferior)
- sacculus
- lagena
- corresponding otoliths
- sound detection/hearing
298
how does equilibrium and balance work
- 3 semicircular canals filled with lymph and detect changes in pitch, yaw, rotation, or acceleration
- each SC has an ampulla with hair cells and a gelatinous cupula that partially blocks the canal
- when fish moves in any direction endolymph moves and bends cupula which is sensed by hair cells that send nerve impulses to balance/equilibrium centre of the medulla
- integration of info from all three ampulla allow proper motor responses of the fish
- ultricus is believed to be main gravistatic organ in fish
299
hearing structures
otolithic organs in pars inferior (lagena and sacculus)
300
how fish hear
- otoliths in gelatinous medium that separates them from sensory macula with many hair cells
- when sound vibrations reach a fish body is moved by water but otoliths are dense and movement lags behind
- otolith movement causes gelatinous medium to move and movement is detected by hair cells
- each hair cell has 2 types of cilia: kinicilium and sterocilia
- movement of sterocilia toward kinocilium increases firing of afferent nerves which is processed by brain as hearing
301
how can swim bladder be used to improve hearing
- gas is more compressible than water and pulsates when exposed to sound
- can use pulsation of swim bladder wall
- need to have a otophysic connection between swim bladder and inner ear
- weberian ossicles: 4 small bones extending from swim bladder to skull
- direct extensions of gas bladder to back of skull
302
function of the lateral line
- detect water movements around fish including velocity and direction
- used to detect prey, school, and avoid obstacles
303
morphology of lateral line
- canal pores open to environment
- neuromasts (similar to ampullae of semicircular canals) lie between canal pores
- canal full of endolymph
- movement of endolymph moves cupula and bends cilia of hair cells
- movement of lymph stimulates neuromasts
304
what are electroreceptors
- allow fish to perceive electric and magnetic fields
- detect difference in voltage between skin and where receptor is located
- present in lampreys, elasmobranchs, a few teleosts
- often concentrated in head area
- uses: prey detection, navigation, communication
305
types of electroreceptors
- ampullary
- tuberous
306
ampullary electroreceptors
- external pit organs
- used in fish that use passive electroreception
- sense low frequency stimuli
- filled with mucopolysaccharide gel
- ampullae of lorenzini in chondrichthyes
307
tuberous electroreceptors
- no opening to the exterior
- found in lampreys and species involved in active electroreception
- sensitive to high frequency stimuli
- located in epidermis
- first thought to be taste or mechanoreceptors
308
electrical communication
- found in knifefish and elephant-nose fish and catfish = weakly electric fish
- some fish use electricity to stun prey - called strongly electric fish
309
how does electrical communication work
- electrical organ discharge produced by modified muscle cells (erythrocytes) in the tail region
- discharge in response to stimulation from spinal motor nerve
310
types of electrical communication
- pulse type: short impulses separated by gaps (clickers)
- wave type: produces continuous waveform (hummers)
311
why do fish modify amplitude, frequency, pulse length, interpulse duration of electrical signals
- species-specific nature of discharge
- provides info about sex, size, maturation state, location, distance, individual identification
- altered by hormones
312
function of electrical communication
- agonistic behaviour (territoriality)
- reproductive behaviour/courtship
- electrolocation
313
how do fish communicate visually
- movements of body structures
- changes in posture
- changes in colour
314
how do fish change colour
- pigments in chromatophores
- located in dermis and sometimes epidermis
315
types of pigments
- melanins: dark colouration
- carotenoids: lipid-soluble, yellow to red
- pteridines: water-soluble, bright yellows and reds
- phycocyanins: blue
- purines: guanine, silvery skin
316
types of colour displays
- static
- dynamic
317
static colour displays
- don't change or change slowly
- informs about species, sex, reproductive condition, danger
- hormones important
- sex steroids, MSH, MCH
- changes in number of chromatophores
318
dynamic colour displays
- rapid change
- exposure of coloured concealed areas
- under nervous/hormonal control
- noradrenaline, adrenaline, acetylcholine
319
light production in deep-sea fish
- bioluminescence (depends on enzyme luciferase)
- found in photophores with and without symbiotic bacteria
320
how many fish can produce sound
50 families
321
mechanisms of sound production
- stridulation
- release of gas from swim bladder or anus
- drumming
- hydrodynamic production
322
stridulation
- grinding or rubbing together of skeletal parts
- clicks, scratches
- 100-8000Hz
323
drumming
- using muscles attached to swim bladder from skull or vertebrae or are incorporated into swim bladder wall
- up to 1000Hz
324
hydrodynamic sound production
- when a fish quickly changes direction or velocity
- restles or roars
- low frequency
- schooling
325
purpose of sound production
- reproductive behaviours: mate attraction, timing of gamete release
- agonistic behaviours: territory defense, fighting
- warning/release responses: startle predator
326
chemical communication
involves release and reception of pheromones by gustation or olfaction
327
pheromone
- chemical substance secreted externally that influences the physiology or behaviour of other animals of the same species
- amino acids, bile salts, nucleotides, gonadal steroids
328
functions of chemical communication
- reproductive cues: recognize mates/young, courtship
- marking territory
- alarm substances
329
how do alarm substances work
- H3NO
- catfishes, characins, knifefishes
- produced in epidermal alarm cells of head and anterior body following injury
- sends message to schoolmates and other closely related species to take escape actions
330
fish
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