Bio 102 - LAB > Lab 7 > Flashcards

Lab 7 Flashcards

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1
Q

Mollusca

A

a lot of them are seafood
- oysters, snails, squid, mussels

also used in architecture and art

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2
Q

Adaptive Radiation

A

adaptive radiation = rapid evolutionary changes within one lineage that produces a lot of descendent species with a wide range of adaptive forms

evolutionary radiation = pattern of evolution where multiple divergences from a common ancestor in a short period of time happened

  • if radiation happens with ecological divesification then it’s = adaptive radiation
    ***in adaptive radiation, the genetic differences between populations evolves because of differences in the environments they live in
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3
Q

Radiation History

A

Molluscs went under radiation around 600 million years ago
- 8 descendant lineages (classes) survived

4 lineages:
- Polyplacophora (chitons)
- Gastropoda (snails and slugs)
- Bivalvia (clams, oysters, mussels)
- Cephalopoda (squids, octopuses)

***mollusca and annelida are most closely related

tree:
- platyhelmines, then mollusca and annelida

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4
Q

Mollusc Traits

A

Bilateral symmetry, triploblast, coelomate, unsegmented protosotomes (spiralia)

  • have complete gut with regional specialization, kidneys and circulatory system that is open in most (some of them have closed)
  • they do gas exchange mostly with their gills but some have evolved a primitive lung
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5
Q

Plasticity

A

the molluscan body plan has high plasticity
- the body plan can be molded like a plastic so it can fit different ecological niches

***mulluscs are very successful because they have extreme plasticity and can adapt

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6
Q

Molluscs Model

A

They aren’t segmented
- but, they are made of some basic unit that can be changed in the same way segments are

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7
Q

Basic Parts of Mollusc

A

basic parts are the ventral foot, dorsal visceral mass, mantle, and shell

  • generalized mollusc isn’t a thing
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8
Q

Class of Mollusc: Bivalvia

A

two shells that are dorsally hinged
- suspension feeder

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9
Q

Class of Mollusc: Polyplacaphora

A

broad flat foot and shell is divided into 8 plates

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10
Q

Class of Mollusc: Gastropoda

A

most have coiled shell
- well defined head and foot for crawling
- largest class of molluscs

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11
Q

Class of Mollusc: Cephalopoda

A

free swimming
- have very developed nervous system
- predator
- their foot is modified into tentacles
- most don’t have a shell

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12
Q

Coelom and Hemocoel

A

coelom is reduced
- it exists only in fluid filled space surrounding a heart

hemocoel = principle body cavity
- made of blood-filled sinuses (spaces) surrounding the internal organs
- homocoel is the functional hydrostatic skeleton

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13
Q

Ventral Foot

A

the ventral side (underside) is made of a broad, flat, muscular foot
- the muscular foot is involved in locomotion (movement)

  • waves of contraction happen to work against the fluid in the hemocoel to make a forward movement
  • they make mucus to help locomotion
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14
Q

Head with Radula in the mouth

A

the radula is a ribbon of teeth
- the teeth are made of chitin and placed in rows
- they move back and forth by set of muscles
- chitin = polysacharide

radula is feeding structure located within the mouth cavity:
- radula is pulled over food particles (think of algae growing on rocks)
- this process breaks off piece of food and bring them into the mouth

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15
Q

Dorsal Visceral Mass

A

the internal organs are concentrated in a region on top of the of the foot called the dorsal visceral mass

  • by having all of the soft, vulnerable internal organs in the dorsal region, they can all be protected by the shell
  • circulatory system, reproductive system, excretory system and digestive system organs are in the visceral mass
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16
Q

Mantle

A

sheet of skin that is located between the visceral mass and the shell

*the mantle secretes the shell

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17
Q

Mantle Cavity

A

the space between the outside wall of the visceral mass and the mantle = mantle cavity
- this space is open to the environment

the digestive system empties waste into the mantle cavity via the anus
- the kidney and gonads also empty their products into the mantle cavity

  • gills also located inside the mantle cavity
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18
Q

Gills

A

the gills are covered with cillia that create a current that draws water into the mantle cavity and over the gills

  • blood inside the gills and it contains O2 binding molecule (hemocyanin)
  • O2 diffuses from the water into the blood in the gills
  • then hemocyanin binds to the O2
  • when the blood reaches cells of the body it releases O2 to the cells
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19
Q

Shell

A

made of calcium carbonate
- deposited in a framework of protein

  • secreted by the mantle
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20
Q

Nervous System

A

has a ganglion that circles the esophagus and nerve cords extend to the organs and foot

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21
Q

Movement

A

the hemocoel is the hydrostatic skeleton
- the muscles contract in waves that work against the hemocoel, which produces movement

  • the foot secretes mucus which helps it move
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22
Q

Open Circulatory System

A

the blood is pumped by a heart into vessels (blood leaves the vessels)
- the vessels come to an end and the blood flows into the spaces or cavities around the cells

  • the blood is drawn back into the vessels and then goes back to the heart

hemocoel = cavity around the cells where the blood flows
- gases and nutrients exchange between the cells and the blood in the hemocoel

*blood flow is slow in open circulatory system because it empties into a big space and the pressure can’t be maintained
- less efficient than closed circulatory system

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23
Q

Getting Nutrients

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A

complete digestive tract:
- made of mouth, esophogus, stomach, intestine, anus

  • the radula is in the mouth
    ***there is a digestive gland in the stomach that secretes digestive enzymes

***in the intestine, digested nutrients are absorbed into the blood and then carried to all parts of the body by blood circulation

24
Q

Gas Exchange: 2 Step Process

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A

heart (muscle) pumps blood through vessels leading to the hemocoel

step 1: exchange within environment and blood:
- gas exchange happens between the gills and the surrounding water

step 2: exchange with the blood and the individual cells
- gas exchange happens between blood in the hemocoel and the cells
- blood then returns to the gills

***in both O2 go in, and CO2 goes out

25
Excretion of Nitrogenous Waste
acquatic molluscs = ammonia terrestrial molluscs (snails and slugs) = uric acid (semi-solid waste) - requires more energy to make but conserves water they have a kidney that is related to the coelom - nitrogenous waste moves from the blood into the coelomic fluid and then is filtered by the kidney - anything the body needs to retain and doesn't want to get rid of is reabsorbed into the blood - the rest leaves the body and enters the mantle cavity
26
Feeding Strategy
Grazing = slowly moving over a surface and ingesting vegetation as they go suspension feeding = removing food from water current predation = actively hunting and capturing food - a very mobile mollusc needs a body plan for speed and agility - so a more effecient circulatory system is needed *greater mobility = more sophisticated nervous system and sensory structures
27
Closed Circulatory System
- blood in vessels has higher pressure and faster delivery of O2 to cells - blood stays in the vessels - gases and nurtients exchange between the cells and blood in vessels
28
Gills - Specialized Gas Exchange Structure
many thin, folded layers - cillia on the surface - a blood vessel carries blood to the gill and one blood vessel carries it away - the blood in the layers will exchange O2 and CO2 with the surrounding water being circulated across them
29
Circulation and Gas Exchange - 2 Step Process
HELP
30
Complete Digestive Tract - Process
the radula scrapes food from the surface and tears the food into smaller pieces - chemical digestion is more efficient if the food is in smaller pieces because this increases the surface area of the food which increases the area for enzymes to work with it - they have regional specialization and complete digestive tract ***radula = mechanical digestion ***stomach and digestive gland = chemical digestion and absorption - the intestine = caries indigestivles to anus where they get eliminated **food waste is eliminated out of anus into water of the mantle cavity and then into surrounding environment
31
Excretory System, Kidney
similar to annelids, the excretuion of nitrogenous waste - excretory organ = kidney ***terrestrial molluscs has uric acid as their nitrogenous waste ***nitrogenous waste moves from the blood to ceolomic fluid (fluid in ceolom surrounding the heart) step 1: unselective filtration - kidney filters coelomic fluid unselectively step 2: selective reabsorption - the kidney reabsorbs useful molecules in the kidney tubule into the blood step 3: excretion the nitrogenous waste gets secreted into the mantle cavity, and then the water carries it away from the body
32
Centralized Nervous System
the molluscs have an anterior brain and pair of ventral nerve cords foot: hemocoel serves as hydrostatic skeleton - muscle contraction puts pressure on blood in the hemoceol which transmits prressure to the parts of the foot and makes movement
33
Class Bivalvia (muscles, clams, scallops, oysters)
they have a bivalve shell: 2 shells that are hinged together dorsally - the shell completely covers the animal and all parts of it can be brought inside the 2 valves closed (think oyster) - bivalves are laterally compressed (flattened side to side)
34
Bivalve Feeding Strategy
they are active suspension feeders - there is cilia on the gills make a current of water flowing thru (called the incurrent siphon) - food particles are trapped in gill filaments as water flows thru them - the cilia move food particles to food groove on ventral edge of the gill and then anterior of labial palps - the labial palps sort the food by size and pass food to mouth for ingestion - anything not passed to the mouth goes into mantle cavity and is carried out with water leaving thru siphon
35
Bivalve Foot
The foot is laterally flattened **the foot is wedge shaped for more effecient digging - bivalves use the the foot for digging by using the hydrostatic skeleton of the hemocoel to extend it and push the sand aside - they avoid predators well beacuse they are burried in sand most of the time
36
2 Step Process of Gas Exchange
step 1: water enters mantle cavity thru incurrent siphon - water goes across gills and leaves thru excurrent siphon - then there's gas exchange between deoxygenated blood in gills and water in mantle cavity (O2 to blood and CO2 to water) step 2: - gas exchange between blood in hemocoel and cells and then back to the gills - oxygen to the cells - CO2 to the blood ***the heart pumps oxygenated blood to the body where it leavs the vessels and flows into the space in tissues called the hemocoel
37
Mussel Disection
the anterior and posterior adducter muscles hold the valves together - the adductor muscles get cut in order to open the shell - the foot is very stiff (in the live mussel it's very flexible) - the gills have cilia on their surfaces and draw water into the mantle cavity - the cilia on the gills help move the food forward to the labial palps which are 2 flaps of tissue at the anterior end close to the mouth
38
Digestive and Reproductive Structures in Visceral Mass
the food is passed to the mouth by labial palps - digestive gland in stomach secretes digestive enzymes - chemical digestion happens in the stomach - absorption of digested nutrients happens in digestive gland and intestine --- nurtients move into blood in hemocoel and then carried around body *the intestine winds thru the visceral mass and then passes thru the ceolom with the heart wrapped around it - undigested materials exists thru the anus into mantle cavity
39
Nervous System of Bivalve
it's less centralized and doesn't have a distinct head - sensory organs in foot, mantle margins, and siphons (these regions have more contact with the environment) - they have similar ganglia as other molluscs but the nervous system is less centralized bc the ganglia are places around the body - basic head with no sensory structures
40
Squid Dissection
squids are predators - mantle is a thick walled muscular structure that covers visceral mass - the suckers on the arms and tentacles are formed from a modified foot circulatory system: closed - they have veins carrying deoxygenated blood from body to gill hearts - gill hearts: they get the deoxygenated blood from veins and pump it to the gills (there's one at the base of each gill) gills: gas exchange between blood and water in mantle cavity - O2 enters the blood and CO2 enters the water systemic heart: vessels carry oxygenated blood from gills to systemic heart which pumps it out to the body arteries: - carry Oxygenated blood from systemic heart to body where oxygen moves from blood to cells and CO2 moves from cells to blood
41
Squid Movement
they move by jet propulsion - during jet propulsion, water is taken into the mantle cavity by expansion of the mantle - then mantle contraction causes water pressure in the mantle cavity to increase and forces water out of the funnel/siphon - the quid uses stabilizes fins on its sides to help them control jet-propelled movement *cloud of ink released by the squid with the outflow of water to hide from predators while they swim away
42
Reproductive Systems: Cephalopods
the cephalapods have separate sexes female - ovary produces eggs male - testis produces sperm - during copulation, the male places the sperm packet with his arm into the mantle cavity of the female - female holds egg capsules in her arms and fertilizes them with sperm - she attaches the fertilized egg capsules to a surface
43
Squid Reproduction
the male deposits packet of sperm in female mantle cavity - the female releases eggs in packets and fertilizes them with sperm - the packets of fertilized eggs attached to susbtrate where they develop and hatch
44
Chromatophore: Cephalopod Camo and Communication
chromatophore= pigment sac that can be expanded or decreases in size by muscle contractions - to hide from predators and their prey, the cephalopods can sense their environment and change their skin color and skin texture using chromatophores to camoflauge - each chromatophore is attached to a nerve ending which is directly linked to brain *chomatophores use useful adpation for protection and for being ambush predators (ex: octupus)
45
Squid Eye and Beak
it has a camera eye - they don't have a blindspot like humans do the squids have a buccal bulb which is a modified pharynx - powerful set of jaws
46
Squid Dissection - Digestive
the esophagus is a long tube that carries the shredded food into the stomach cecum: food passes into the cecum - thin walled sac that is on top of gonads *digestion and absorption happens in the cecum - the food continues into the intestine and then it goes back into the direction of its head
47
Squid Dissection - Reproduction
sperm are placed in packets called spermatophores - the male uses a tentacle and then places a spermataphore in the mantle cavity of the female - the eggs are released into the mantle cavity and fertilized there - the fertilized eggs are packaged with nutrients and a shell - the female attaches the eggs as clusters to plants or other thing on the sea floor
48
The Pen in Squid
the squid doesn't have a shell - instead they have a pen that is an internal skeleton made of chitin - lies on back of the mantle - pen helps with support, stability and leverage for muscles of mantle
49
Squid Nervous System
cephalopods have most developed nervous system out of the all the invertebrates - brain is made of fused ganglia that circle the esophogus - esophogus is encased in cartiliginous cranium stellate ganglia: they control the synchronous contraction of the muscles on the mantle
50
Gastropoda - Slugs and Snails
largest and most diverse class of molluscs - live in saltwater, freshwater, and on land - they are herbivores, carnivores, suspension feeders... - some have shells and some don't - some use gill and some use lung 75% of molluscs are snails
51
Gastropoda Shell
the shell is one piece and spiraled - shell is elongated in the dosral ventral axis and the raised off of the foot - the entire body of the snail can be withdrawn into the shell for protection
52
Torsion in Gastropods
torsion only happens in gastropods (no other type of mollusc) torsion = process during development that results in rotation of the visceral mass and mantle on the foot - so now the mantle cavity (including the anus) lies in the anterior body over the head and the mouth, and gut and nervous system are twisted
53
Postion of Mantle Cavity as a Result of Torsion
water snails: - have gill now located in the anterior of mantle cavity terrestrial: - have lung - can't have a gill because of its large surface area would make the gill dry ou t - the lung is a vascularized (has lots of blood vessels) walls of the mantle cavity - gas exchange occurs between the air in the mantle cavity and the blood
54
Aquatic Lettuce Slugs
slugs = gastropods without a shell - they eat algae and use chloroplast - slug can get energy from the the sunlight for many weeks - air enters thru lung
55
Polyplacaphora, Chitons
chitons live in the intertidal zone - at low tide they get exposed to air - at high tide they are exposed to water - they adhere to uneven rocky surfaces - they feed on organisms encrusted on rocks like sponges and algae - do grazing feeding strategy - they have low degree of cephalization - foot is broad and flat -- used for locomotion and adhering to rocks, suction cup
56
Polyplacaphora - Mantle
the mantle can extend past the shell - when it's exposed to air at low tide, the mantle can come in contact with rocks and seal off the mantle cavity and visceral mass from the environment - gills are located in the 2 mantle cavities shell = made of 8 plates
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