Zoo 102- Lab 7 and 8 Quiz

Ventral Foot

Locomotion

Dorsal Visceral Mass

house digestive, reproduction, excretory organs

Mantle

secretes the shell

Mantle Cavity

space between mantle and visceral mass

Shell

protection

Radula

scrapes food off surfaces or shreds food into smaller pieces

Mollusca: coelom

reduced to space around the heart

Mollusca: Hemocoel

series of interconnected spaces between tissues and organs

blood leaves vessels and flow through these spaces outside of vessels

Mollusca: Circulatory System

distributes gases, nutrients, nitrogenous wastes

open circulatory system (non- cephalod molluscs)

Open Circulatory System

-fluid is called hemolymph rather than blood

-blood leaves vessels and enters hemocoel

-gas exchange between blood and cells

Closed Circulatory System

blood is maintained at higher pressure and tehrfore reaches all parts of body faster

more efficent for more active animals with higher metabolus raters

gas exchange between blood in capillaries and cells

Characteristics of Gas Exchange Surface

-large surface are

-thin (diffusion distance constraint)

-highly vascularized (supplied w blood vessels)

-moist surface

Gills

specialized gas exchange structure in molluscs

Mollusca: Circulatory and Respiratory Systems

gills (or other vascularized structure) exposed to environment in mantle cavity where gas exchange occurs between environment and blood

water (high in oxygen) is brought into mantle cavity ventrally by movement of cilia, makes a U-turn and goes back out dorsally

deoxygenated blood is brought to the gills from the hemocoel of the body

as water flows over teh gulls oxygen diffuses into blood and carbon dioxide diffuses out (GAS EXCHANGE)

oxygenated blood flows to the heart and then pumped out ot hemocoel of th ebody where gas exchange occurs between blood and cells; oxygen diffuses from blood to cell and CO2 diffuses from cell to body

Mollusca: Digestive System

complete

Process of Getting Nutrients

1) obtain food

2) mechanical and chemical digestion

3) aborption

4) eliminmation of indigestible material

Mollusca: Radula

ribbon of chitinous teeth, moved back and forth by set of muscles, often functions as scraper but can be modified for other uses

Mollusca: Digestive Tract

radula > mouth > esophagus > stomach (> cecum) > intestine > anus

cecum or intestive > hemocoel > cell of the body

Mollusca: Excretory System

function: get nitrogenous waste out of the body

three processes:

1) filtration of coelomic fluid

2) modify filtrate

3) excrete waste

nitrogenous waste-

aquatic = ammonia

terrestial = uric acid

Mollusca: Excretory Tract

cell > hemocoel > heart > coelomic fluid --filtartion-> kidney --modification of filtrate--excretion-> mantel cavity

Mollusca: Nervous System

anterior ganglia = brain

nerve cords send signals to muscles of th efoot

nerve cords send signals to mantle and internal organs

Mollusca: Movement (foot)

secretes mucus

hemocoel serves as hydrostatic skeleton

waves of muscle contraction working against hemocoel produces movement

Four Classes of Molluscs

Polyplacophora (chitons)

Gastropoda (snails and slugs)

Bivalvia (clams mussels, scallops, oysters)

Cephalopoda (squid, octopus, cuttlefish, nautilus)

Cephalopoda: Female Reproductive System

accesory galdns secrete a shell around the egga and a membranous capsule containing 200 eggs

releases 20-30 capsules of egges into the mantle cavity where they are fertalized by sperm exiting the spermatophore

attaches the egg capsules in a mass to objects on the sea floor

Cephalodpoda: Nervous System

brain = fused ganglia that encircles the esophagus, encased in a carilaginous cranium

stellate ganglia= control synchronous contraction of the muscles of the mantle, give rise to the giant fiber system

Pilyplacaphora: Mantle, Head, Food

extends past the shell

no cephalization

broad and flat, used for locomotion and adhering to rocks

Gastropoda

no typical gastropod

largest and most diverse calss

lives in saltwater, freshwater, and on land

herbivores, carnivores, filter feeders, scavengers, parasites

w/ or w/o shell

gills or lungs

Helix Snails

terrestial- two pairs of retracile tenatcales on head (upright ones have eyes and shorter have chemosensory organs)

has a lung

Arthropod Success Defined

diversity, abundance, distribution

Arthropod Success Reasons

-modular body plan (segmentaion and tagmatization)

-versatile exoskeleton (adaptation to terrestrial life)

-small size

-variety of gas exchange strategies (adaptation to terrrestrial life)

-complex behavior and evolution of social systems

-complete metamrphosis (different stages of life use different parts of habitat reducing competition)

-excretion of uric acid (adaptation to terrestrial life)

-internal fertilization (adaptation for terrestrial life)

-flight

Arthropod: Segmentation vs Tagmatization

segmentation:

-modular body, repeated units

-independent evolution of genes that regulation different segments

tagmatization:

-segments fuse to form functional groups = tagmata

-specialization of appendages associated with different tagmata

Arthropods: Exoskeleton

formed from versatile cuticle

hard enough for portection

light enough for mobility

consists of proetin and chitin (polysaccharide)

functions:

-protection barrier, keeps some things in and others out: prevents loss of water, desiccation, from body and prevents pathogens adn parasites from entering

-responible for structire, support and form

-movement: rigid skeleton for muscle attachment, and sofat adn flexible at hinge (like joints)

-sensing: cuticle an integral part of structure of sensilla (sensory receptors for chemical, temperature, touch, and humidity)

Ecdysis: shedding of exoskeleton (vulnerable)

Arthropods: Muscles

attached to inside of skeleton in bands that are antagonists on different sides of joint

type of muscle: striated (contracts more quickly)

Arthropods: Constraint on Size

molting (shed exoskeleton soft body would deform if too big)

exoskeleton weight and strength (too large, would crumble)