1
Q
What does ‘ecdysozoa’ mean?
A
” to strip off”
2
Q
What are the ecdysozoan phyla?
A
- nematoda; roundworms
- Nematomorpha; horsehair worms
- onchophora: velvet worms
- tardigrade: water bears
3
Q
Describe the phylum Nematoda?
A
- roundworms
- very abundant all over the world; high human impact
- most important of all parasitic animal groups
- echo/endo parasites
- adapted mouth parts: hooks, etc
- reproduction (100,000s of eggs)
- thick cuticle (collagen) for defence/support
- fluid filled pesudocoeloem functions as hydrostatic skeleton
- no circular muscles *4 quadrant extend to pseudocoeloem; antagonistic muscle support from cuticle)
- thrashing motion in water, more controlled in soil
4
Q
What does the Nematode use for defence and support?
A
- a thick cuticle (collagen)
5
Q
What development do nematodes have?
A
pseudocoelomate; hydrostatic skeleton
6
Q
What are some common examples of Nematodes
A
–> intestinal roundworms
–> hookworms: blood suckers
–> pin worms: don’t require intermediate host, most common parasite of developed countries!!
–> filarial worms: arthropod transmission; mosquitos are normally intermediate host
–> Caenorhabditis elegans
- free living, important experimental biological models
7
Q
Describe Caenorhabditis elegans
A
- Phylum Nematoda
- free living; non hazardous/infectious/pathogenic
- one of the most important experimental biological models
- all 959 cells traced from zygote to adult
- entire nervous system known
- genome entirely mapped, all 19,820 genes sequenced
8
Q
Describe the Phylum Nematomorpha
A
- horse hair worms
- pseudocoelomates
- semi parasitic (drinking/eating)
- adults are free living, parasitic in arthropods as juveniles
- parthenogenetic (no males, diploid female eggs)
- intermediate and definitive host for development ; free living reproduction
- encysts on vegetation or intermediate host
9
Q
What is the Clade Panarthropoda? What phylum are found in the Panarthropoda?
A
- small coeloem
- ventrolateral appendages/walking pairs
- hemocoel and open circulatory system (blood + lymph = hemolymph)
–> includes: phylum onychophora, tardigrada, and arthropoda
10
Q
Describe the phylum onychophora
A
–> velvet worms
–> 500 million yr history in fossil record, originally marine
- like moisture
- caterpillar like
- mostly predators with snails (glue like slime)
- soft cuticle repels water (eg; velvet)
- 14-43 pairs of unjointed legs with pad and 2 claws
11
Q
Describe phylum tardigrada
A
of the clade panarthropoda
- water bears
- mosses, lichens
- microscopic
- 8 unjointed legs with claws
- pairs of sharp stylets and a sucking pharynx: piercing and sucking plant juices or other small invertebrates
- parthenogenetic or sexual
- cryptobiosis –> tun state : withstand extreme environments
12
Q
Describe the organization of the ecdosozoans
A
- organs, bilateral symmetry, triploblasts, protostomes
- nematodes and Nematomorpha: pseudocoelomate (hydrostatic skeleton)
Onychophora and tardigrada: no segmentation but serial separation or patterning
13
Q
Where in the phylogenetic tree are arthropods located?
A
–> Bilateral –> protostomes –> ecdosyzoans –> panarthropods –> arthropods
14
Q
Describe the Phylum Arthropoda
A
- most diverse animal phylum (80% of named animals)
- good and bad for human importance
- inverts with segmented bodies, jointed limbs, exoskeleton made of chitin
- Synapomorphies:
- compound eye, 1 pair of antennae, chitinous exoskeleton with articulated appendages
15
Q
What is an arthropod?
A
- inverts with segmented bodies, jointed limbs, and an exoskeleton made of chitin
16
Q
Why are arthropods so diverse?
A
- Exoskeleton: chitinous cuticle = protection/mobility
BUT must most to grow bigger - segmentation and appendages: specialized functions, locomotion
- Respiration –> metabolism
- sense organs; highly developed
- complex behaviour; hierarchies
- metamorphosis; more niches
17
Q
What are tagmata?
A
- in arthropods; groups of segments that work together for a common function
- head, thorax, abdomen
- 3 or 2 tagmata (some fused)
18
Q
What are the fused tagmata called?
A
cephalothorax: head and thorax fused
fused in 1 stigma: called a trunk (eg; myriapoda have a head and trunk)
19
Q
What are the foot anatomy terms for arthropods
A
biramous: 2 points at end of foot
uniramous: 1 point at end of foot
20
Q
What are the subphylum of the phylum arthropoda?
A
- chelicerata
- myriapoda
- crustacea
- hexapoda
21
Q
Describe the subphylum chelicerata
A
- horseshoe crabs, spiders, ticks, scorpions, sea spiders
- 2 tagmata; cephalothorax(prosoma) + abdomen (opisthoma)
- appendages:
- no mandibles, no antennae
- 1 pair of chelicerae, 1 pair of pedipalps, 4 pairs of walking legs (distinguished from insects)
- most uniramous, some biramous
22
Q
What is one way to identify chelicerate from the Hexapoda
A
chelicerata have 4 pairs of walking legs
23
Q
Describe the subphylum myriapoda
A
- centipedes and millipedes
- two tagmata: head and trunk
- appendages:
- mandibles, 1 pair of antennae, 1-2 legs/segment, uniramous
- centipedes are more flattened/carniverous, millipedes: rounder, herbivorous
24
Q
Describe the subphylum crustacea
A
- mostly marine, also FW, terrestrial
- two tagmata: cephalothorax, abdomen (some exceptions)
- appendages: 2 pairs of antennae, mandibles with two pairs of maxillae, 1 pair of walking legs/segment, all biramous (except 1st antennae)
25
Describe the crustacean body plan
- two tagmata
- cephalothorax: head (feeding and sensory) fused w/ thorax (locomotion and respiration) ; 13 segments
- abdomen: locomotion and reproduction; 6 segments
carapace: dorsal head cuticle covers head and thoracic sides
26
Describe the internal systems of the crustaceans
- OPEN circulatory system
- pumping heart (not all), limbs help move hemolymph around
- gills attached to appendages
- excretory/osmoregulatin through antennal glands
27
Describe the sensory system of the crustaceans
- advanced nervous system
- median eye and compound eyes (compound eye similar to insects, good at detecting motion/polarized light)
- statocysts, tactile hairs
- chemosensory > taste and smell
28
Describe reproduction in crustaceans ?
- most dioecious and internal fertilisation
- most brood eggs (female keeps/protects)
- larval stages
29
What is ecdysis?
- in crustaceans, 'moulting'
- gets rid of old skeleton and new skeleton is soft and eventually re hardens
- typically moult from centre of their body
30
Describe feeding in the crustaceans
- maxillipeds, maxillas, mandibles = hold/shred food
- claws (chelipeds) and walking legs: food capture, piercing/crushing
- predators, scavengers, deposit feeders, parasites, filter feeders
31
What is class Ostracoda?
of the crustaceans
- bivalved carapace
- specialized head
- reduced thoracic appendages and abdomen
32
Describe class Branchiopoda?
- of the crustaceans
- legs for suspension feeding
- many freshwater - sea monkeys!
33
Describe class Copepoda
- crustaceans
- no carapace
- no legs on abdomen
- nauplius eye
- high fat content
34
Describe class thecostraca, subclass Cirripedia
- crustaceans
- barnacles!
- calcareous shells and sessile
- long thoracic legs
- reduced head and abdomen
35
Describe class Malacostraca
- of the crustaceans
- each segment has an appendage
36
Describe order Isopoda
- of the crustaceans
- dorsoventrally flattened
- no carapace
- eyes flat (not stalked)
- inc. terrestrial spp
37
Describe the order amphipoda
-crustaceans
- laterally flattened
- no carapace
- eyes flat (not stacked)
- eg; beach fleas
38
Describe Order euphasiacea
- huge food source eg; krill
39
Describe the order Decapoda
- crustaceans
- first walking leg pairs. modified into claw (eg; chiliped)
eg; crabs, lobster, shrimp
40
Why are crustaceans important
- plankton and the food chain
- mutualistic relationships
- parasites
- intermediate hosts of parasites
- food
41
Describe the subphylum Hexapoda
- 6 legged
- three tagmata: head, thorax, abdomen
- uniramous appendages
- unique tracheal system
42
why are insects so diverse?
- flight, small size exoskeleton, minimal water loss, jointed appendages (segmentation), metamorphosis
43
Describe the class insecta
- >1million spp named
- found in every habitat
- all life styles
- diverse
44
What makes an insect
- three tagmata: head, thorax, abdomen
- three pairs of legs and (usually) two pairs of wings on thorax
- 1 pair of compound eyes, 3 ocelli; 1 pair of antennae
- mandible and other mouthparts
45
Describe the diversity of legs in insects
- walking: terminal pads and claws
- jumping: enlarged
- swimming: modified paddles
- mole crickets: front legs adapted for burrowing
- forelegs of praying mantis allow them to grasp prey
- honeybees: leg adaption for pollen
46
Describe the mouths of insects
- mouthparts are specialized for feeding behaviour
- chewing, piercing, sucking, lapping, sponging
47
Describe the wings of insects
- cuticle extensions on thorax (most have two pairs)
- dipterans (flies): two wings
- thin and membranous
thick (forewing in beetle)
- scaly: butterflies/moths
- parchment like - grasshoppers
- no wings: lie, bed bigs, fleas, silverfish
48
What are the ways that insects fly?
- direct flight muscles attach to wing
- indirect flight muscles alter the shape of the thorax to cause wing movement
- figure 8 movement moves insect forward
49
Describe respiration and circulation in insects
- tubular heat pumps hemolymph
- hemolymph does NOT transport oxygen
- tracheal system: tubes bring air directly to cells
- spiracle --> Trachea --> tracheole
--> no cell is more than a few micrometers away from a tracheole
50
Describe the development of insects. What are the different kinds?
- moult between each stage
- 88% undergo holometabolous (complete) metamorphosis
- egg - larvae - pupa-adult
- few undergo hemimetabolous metamorphosis (incomplete)
- few undergo direct development
51
Describe social behaviour of the insects
- eusociality: true social behaviour
- reproductive division of labour, overlapping generations, cooperative care of young
eg; bees, ants, termites
52
Where in the phylogenetic tree are echinodermata located?
Bilateria --> deuterestomes --> ambulacrariata --> echinodermata
53
What is a common feature in deuterestome ancestors?
gill slits in pharynx; this has been lost in some later on
54
Describe the phylum echinodermata
- exclusively marine; mostly benthic.- 5 classes
- lack cephalization (no brain)
- loss of gill slits
- 5 unique features (autopomorphies)
55
what are the 5 autopomorphies of echinoderms
1. pentaradial symmetry in adults
- 2. calcareous endoskeleton
3. water vascular system
4. pedicelleriae
5. dermal branchiae (papillae)
56
Describe pentaradial symmetry in echinoderms
- from a bilateral ancestor
- mouth side = oral, opposite = aboral
- madreporite: allows water in
57
What is the madreporite?
in echinoderms, allows water in
58
Describe the calcareous endoskeleton in echinoderms
--> mesodermal porous endoskeleton
- meshwork of ossicles (eg; plates) from the stream (unique)
- spines and tubercle projections, unique meshwork )porous) of CaCO3 (calcareous)
- connected by mutable "catch collagen" - change from liquid to solid without muscular effort
59
Why are starfish sometimes hard and sometimes soft?
their endoskeleton is connected by "catch collagen" which allows for the switch between liquid and solid without muscular effort
60
Describe the water vascular system in echinoderms
--> hydraulic system
- canals and tube feet
- only open on one end
- specialized coelomic system
--> functions: respiration, excretion, locomotion, feeding
61
What are ambulacra?
- the bands from which tube feet project
62
what is the path of the vascular system
- madreporite --> stone canal --> ring canal --> radial canal --> lateral canal --> ampullae --> podia (tube feet)
63
Describe the pedicellariae of the echinoderms
- usually on aboral surface (all around in sea urchins)
- functions: cleaning, food capture, defence
- look like small spikes
64
Describe the dermal branchiae of the echinoderms
- AKA skin gills
- projection of thin walled coelom
65
Describe the nervous system of echinoderms
- no brain or ganglia
- nerve ring, radial nerves, epidermal nerve net
- sensory cells, eyespots (tips of arms)
66
describe the digestive system and reproductive system of echinoderms
- feeding mode varies
- reproduction: often separate sexes with external fertilisation
67
Describe larval development in the echinoderms
- deuterestome embryology
- bilateral free swimming larvae: left side becomes oral, right = aboral, with tube feet
- metamorphosis to adult form
68
Describe regeneration in echinoderms
- only need 1/3 of central disk and 1 arm
- also able to deliberately send body parts of appendages = autotomy
- used as escape to replacing infected/damage appendages
69
what is autotomy?
when echinoderms deliberately shed body parts or appendages
70
What is fragmentation in echinoderms? How is it different from regeneration?
in linckia comets
- can cast off an arm without any part of the central body attached which will grow into a complete starfish
71
What are the classes of the phylum echinodermata?
- asteroidea
- ophiuroidea
- Echinoidea
- holothuroidea
- Crinoidea
72
Describe the Class Asteroidea
--> star form; seas stars
--> the "poster" echinoderm
- central disc + 5 arms
- 7 -50 arms
--> two part stomach and can evert stomach
--> scavengers and carnivores, can also suspension feed
73
What are two keystone Asteroidea species?
- purple intertidal Seastar - mussel populations
- reef sea star
74
What are the deadly Asteroidea?
- crown of thorns (Indonesian)
- pacific sunflower sea star - biggest sea star in the world
75
What is a threat to sea stars? Describe it
- sea star wasting disease
- white lesions, water vascular systems stop working ("limp")
- fragmentation; death
- associated with warmer temperatures and densovirus
76
Describe the class Ophiuroidea
- brittle stars / basket stars
- abundant (forms carpets)
- move with flexible articulated arms - closed ambulacral grooves, tube feet for feeding - no suckers
- no pedicellariae, no papillae
- madreporite on oral side (unlike starfish)
- no anus (indigestible out the mouth)
- organs with central disc
- fragile with regeneration
- cryptic (away from light)
77
Describe the class Echinoidea
- sea urchins, sand dollars, heart urchins
- compact body within a test (sea urchin shell)
- ossicles as fused plates, some secondarily bilateral
- 5 ambulacra extends up and around towards anus (aboral) - no arms
- tube feet for locomotion w/assist from spines in socket joints (unique!)
- many with venomous pedicellariae (3 jaws)
- mostly herbivorous - Aristotle's lantern with 5 teeth
- sand dollars deposit feeders
78
What is the Echinoidea mouth part called? Where is their anus located?
Aristotle's lantern
- anus loaded on aboral side (opposite of Aristotle's lantern)
79
what are the ecological impacts of sea urchins?
- kelp forest destruction: creates Urchin Barrens
- predators of sea urchins are otters = keystone species
80
Describe the class Holothuroidea
- sea cucumbers
- elongated on oral-aboral axis
- oral tentacles are modified tube feel
- secondarily bilateral
- reduced ossicles
- "ventral" tube feet specialized for locomotion on "sole"
- no arms, benthic= crawl, burrow = no tube feet (circular and longitudinal muscles instead)
81
How do sea cucumbers move?
- benthic: crawlers
- burrowers: no tube feet (circular and longitudinal muscles instead)
82
What are oral tentacles in sea cucumbers?
- modified tube feet for suspension or deposit feeding (important nutrient cyclers)
83
What is the cloaca?
- an all purpose orifice via anus
- for respiration (respiratory tree) and excretion(unique)
- self defence: evisceration of cuvierian tubules, resp. tree, or guts
84
What are cuvierian tubules?
these, Among the resp. tree and guts, are expelled from the cloaca of sea cucumbers
85
What kind of skeleton does the sea cucumber have?
- hydrostatic skeleton and a spacious coelomic cavity
86
How many species of sea cucumber are pelagic?
some are benthopelagic and one is true pelagic
87
Describe the class Crinoidea
- feather stars/sea lilies
- stalk with cirri attached to the aboral side of calyx with many arms that branch into pinnules
- move/crawl/sweep/swim via cirri or feathery arms
- no pedicellariae, no madreporite, no spines
- mouth and anus on ORAL side
- many deep water - some feather stars in shallow
88
What are sea lilies? What are feather stars?
- class Crinoidea
- flower shaped on top of stalk attached to substrate
- short stalk w/ many branched arms
89
In the crinoidea, where are the mouth and anus located?
the ORAL side
90
Where in the phylogenetic tree are the hemichordata?
- deuterestomia --> ambulacraria --> hemichordate
91
What are the hemichordata?
- "half chordates"
- gill slits (like all deuterestomes)
- have a stomochord: evagination of mouth cavity (not notochord, no chordate)
- 3 part coelom
92
Why isn't a hemichordate classified as a chordate?
They have a stomochord, not a notochord
93
What are the classes of hemichordata?
- Class enteropneusta
- class pterobranchia
94
Describe class enteropneusta?
Of the Hemichordata
- acorn worms,
- solitary, marine, deposit/suspension feeders vis mucus on proboscis
95
Describe class pterobranchia
- of the subphylum hemichordata
- smallest use dwelling, colonial, marine
- suspension feeders via crown of tentacles with coelomic extensions
96
Describe the body organization of echinoderms?
- organs, pentaradial symmetry, eucoelomate, triploblasts/deuterstome, no segmentation
97
Describe the body organization of the hemichordates?
- organs, bilateral symmetry, eucoelomate, triploblast deuterostome, no segmentation
98
describe the location on the phylogenetic tree of chordates
- bilateria --> deuterestomes --> chordata
99
Describe phylum chordata
- bilateral, anterioposterior axis, coelom, tube in tube, metamerism, cephalization
100
What are the phyla with segmentation
- annelids, arthropods, chordates
101
What are the 5 classic chordate characteristics?
1. Notochord
2. Dorsal Hollow Nerve Cord
3. Pharyngeal pouches and slits
4. endostyle or thyroid gland
5. postnatal tail
102
what is the notochord?
- rodlike, semirigid tissue enclosed in a sheath
- extends the length of the body lying between the gut and nervous system
- mainly to stiffen the body: providing skeletal scaffolding for the attachment of swimming muscles (support)
- always found at some embryonic stage
- 1st part of the endoskeleton to appear in the embryo
- in non vert chordates and jawless vertebrates: PERSISTS through life
- in most vertebrates (displaced by vertebrae, reman as discs)
103
Is the notochord found in both vertebrates and invertebrates?
Always in invertebrates and jawless vertebrates: persists through life
- in most vertebrates: displaced by vertebrae, remains as discs
104
Where and what is the dorsal hollow nerve cord?
- in chordates: dorsal to digestive tract (ventral to digestive tract in non chordate inverts eg; insects)
- anterior end = brain
- via neurulation ie; ectodermal region
- passes through the neural arches of vertebrae (if vertebrates) or runs dorsal to notochord if no vertebrae
105
In frog gastrulation, where does the formation of the dorsal hollow nerve cord occur?
from the ectoderm
106
What are pharyngeal pouches and slits?
- from the in pocketing of the ectoderm + invagination of endoderm and pharynx
- perforated pharynx functions as filter feeding apparatus in non-vert chordates (lancelets and tunicates)
- post embryonic secondary development in some vertebrates (eg; auditory tube, middle ear, glands, larynx)
- fishes added a capillary network within gas permeable walls = led to evolution of gills!
107
What is the endostyle/thyroid gland?
- longitudinal ciliated groove central to pharynx
- some cells in endostyle secrete iodinated proteins homologous with the iodinated hormone secreting thyroid gland of adult lampreys and the remainder of vertebrates
- secretes mucous for food capture in the filter feeding non vertebrate chordates
108
Describe the post natal tail
- post natal tail+ musculature: motility for larval tunicates and amphioxus to swim
- efficiency increased in fished but became smaller/vestigial in later lineages
109
What is the earliest known chordate?
- pikaia - 510 mya
- similar to living cephalochordate, and originally classified as a polychaete
- notochord and segmented muscles
110
describe the subphylum cephalochordata
Poster chordate
- amphoioxus (point at both ends)
- branchiostoma: Gill mouth
- lancelets
--> burrow in porous mud/sand
- exposes mouth toe seawater and filters out particles
- water enters the mouth drain by cilia in the buccal cavity and the pharynx
- passes through pharyngeal slits where food is trapped in mucus secreted by the endostyle
- closed circulatory system (no heart)
- moderate cephalization - no distinct brain or cranium
- body surface respiration
111
Describe the subphylum Urochodata
AKA tunicates
- in all seas and depths
- most sessile as adults, some free living
- tunic (cellulose)
- filter feeders
- no cephalization
- two directional heart
- two siphons
112
What are the two classes of tunicates?
1. Ascidiacea
- sea squirts
- thaliacea; sales
2. appendicularia
113
How do we know that tunicates are chordates?
laurel stages show all 5 classic chordate characteristics
114
Describe class Ascidiacea
- of the Urochordata
- sea squirts
- "little bag"
- compound, colonial, solitary
- aquaculture's worst enemy
- eg; mouth from the deep and skeleton panda
115
Describe theliacea
- of the class Ascidiacea
- "luxurious"
- the sales
- free swimming, can be solitary or colonial
- use water currents for feeding and gas exchange and locomotion (jet propulsion)
- feed using a mucus net
116
Describe class Appenicularia
- of the Urochordata
- "small appendage"
- AKA Larvaceans: "ghost larvae" - pelagic, free swimming, tiny
- show all 5 chordate characteristics in the adult form
- secretes a mucous house to suspension feed
117
Describe the organization of the chordates
- organs, bilateral, bilateria - deuterestomes, triploblast, segmentation!
118
Where in the phylogenetic tree is the subphylum vertebratea located?
--> Bilateria --> deuterestomia --> Phylum chordata --> Subphylum vertebrata
119
What percentage of animal species are vertebrates? Why should we care about them?
~2-5%
- conservation!
120
What is the IUCN?
International Union for Conservation of Nature
- government + civil society organizations united: protecting nature and conserving life on earth
- most comprehensive inventory of global conservation status of species
121
What does conservation biology mean ?
protecting earth's biodiversity: species, habitats, ecosystems
122
What are the masse extinctions?
1. Ordovician - 86%
2. Devonian - 75%
3. Permian - 96%
4. triassic - 50-75%
5. cretaceous: 75%
6. Holocene - now
- Anthropocene sixth mass extinction? - 83% wild mammals, 80% marine mammals, 15% fish vanished
123
What Australian vertebrates have gone extinct? Elsewhere?
- marsupials, flightless birds, tortoises
- mastodons, mammoths, giant sloths gone 10k years ago
124
how many planets are required if we all lived like an average US citizen?
3.9 earths
125
How much has the population of vertebrates fell by since 1970?
60%
126
Which habitat species are the most impacted?
- freshwater species: -81%
terrestrial : -38%
- marine: -36%
127
What does successful species conservation look like?
- maintain multiple populations across ecological settings
- populations should be sustaining, healthy, genetically robust
- resilient to climate and other changes
128
What is the neural crest?
"4th Germ Layer"
- quadroblastic
- develops into trunk and head (vert. synapomorphy)
129
Describe the features of the subphylum vertebrate (craniata)
- neural crest: Quadroblastic --> anteriorly lead to tripartite brain (forebrain, midbrain, hindbrain)
- forebrain houses the cerebral cortex: the main processing centre of the brain
- mineralized tissue (cranium (eg; skull) and vertebrae (surround/protect nerve cord))
- pair of semi circular canals
- ectoderm places (epidermis thickening --> sensory system eg; teeth, scales)
- homeobox (hot) genes double duplication (head-tail plan)
130
How did vertebrates get so big/fast/smart?
- musculoskeletal modifications : endoskeleton
- physiology
- tripartite brain
131
What are the musculoskeletal modifications in vertebrates?
- endoskeleton:
- permits almost unlimited body size with much greater economy of building materials
- forms excellent jointed scaffolding for attachment of segmented muscles
132
What physiology allowed for vertebrates to get fast/smart/big?
- modifications of digestive, respiratory, circulatory, excretory system to meet increased metabolic demand
133
What is the tripartite brain?
derived from the neural crest
- forebrain: olfactory system
- forebrain houses the cerebral cortex which is the main processing centre of the brain
- midbrain: ocular system
- hind brain: balance, hearing, taste, touch, respiration
134
How long ago did vertebrates originate?
- 525-360 mya
135
What are the early vertebrates?
-Myllokunmingia, 518 mya - like hagfish
- Haikouichthys (518 mya) - (like lampre)
136
What are Myllokunmingia?
- 518 mya, like hagfish
- earliest known vertebrate?
- single specimen
- vertebrate features (like the hagfish)
- no vertebrate but a cranium and segments out from notochord
137
what is the Haikouichthys?
- 518 mya
- single specimen
- vertebrate features: cartilaginous gill supports
- like lampre
138
Are fish monophyletic?
no, referred to as "fishes" because it does not include all of their ancestors (eg; mammals)
139
What is a modern fish defined as?
- aquatic vertebrate with gills, limbs in form of fins, skin covered in scales of dermal origin
140
What are "fishes"
- non monophyletic group
- adaptation, dominant in nearly all aquatic environments
- streamlined for movement through water
- unique lateral lune system
-
141
True or false: the jaw is the same as teeth
FALSE: Jaw provides the ability to open and close mouth
142
What are the jawless fishes?
- AKA Agnatha (without a jaw)
1. extinct "ostracoderms" ("Jawless armoured")
2. Cyclostomata ("Round mouth")
143
What are cyclostomata?
- only living groups = monophyletic
- hagfishes, lampreys
- NO: jaws, internal ossification (no bones), scales or paired fins
- eel like body
- keratin teeth
- single median nostril
144
Describe the ostracoderms
- extinct
- bony armour: dermal plates
- pteraspids and myopterygians
- jawless, armoured, extinct fish
145
Describe the two kinds of ostracoderms
1. Pteraspids : paired nasal openings and three layer dermal skeleton
2. Myopterygians: paired lateral fin folds; dorsal and/or anal fins
146
What are the subclasses of Cyclostoma?
- Class Mixini : Hagfishes
- Class Petromyzontida: lampreys
147
Describe Class Myxini
- Hagfishes
- slime "eels" / hag; predator defense
- only iso-osmatic living vertebrate
- vertebral "elements" in embryo and at tail
- --> bottom scavengers: good sense of touch/smell
- 6 tentacles = barbels to sear out food
- keratinized rasping teeth on a protrusible tongue
- tail to head knot creates pull feeding suction and removes slime
148
Describe class Petromyzontida
Of the Cyclostomas
- vertebral elements along body
- Feeding: suction to the body of fishes with round mouth at the base of oral hood
- protrusible tongue
- anti coagulant
- use oral discs to hold onto rocks
- ectoparasitic and a nuisance
149
Describe the lamprey life cycle
- spawn upstream in FW
- marine forms are anadromous: leave sea as adults to spring upstream, spawn in winter or spring in NA
- osmoregulatory
- ammocoete larvae
- non parasitic forms don't feed after emerging as adults, adults die after spawning
150
What are the gnathostomes?
jawed vertebrates
151
When did jaws originate?
- 450 mya, early silurian
152
Describe the origin of jaws
- 450 mya; early silurian
- from 2 pairs in enochondral cartilaginous articulated arches: mandibular and hyoid arches
- evidence: similar in form, machinery, and origin to gill arches
- note the 2 pairs of pseudo branches anterior to these: derived from mandibular arch
153
Describe the origin of paired fins?
- pectoral and pelvic pairs
- yaw, pitch, roll
- two part hypothesis origins:
1. Finfolds eg; anaspids --> Row of inlets --> paired fins
2. +outgrowths of lateral plate mesoderm tissue
154
What are placoderms?
- the first gnathostomes
- the extinct armoured shined with jaws : ornamented bony shield
- separate head and trunk shield
- mobile joints (head, hinged head/neck, fins) = head lift up during feeding
