lecture midterm 2 Flashcards

Question

new characteristics: Phylum Rotifera

Answer 1

- eutly (fixed number of cells) — develop by cell division until maturity then only cell growth - have lorica (shell-like protective outer covering) - reinforced with sand grains - closed at one end - protonephridia - colonial - small cerebral ganglion

Answer 2

- ciliated corona (for suspension feeding) - mictic reproduction (stressed cycle) - cryptobiosis

Answer 3

helps rotifers and other species survive in fresh water in one of their reproductive stages they can enter into this essentially like a death state, can dry up completely, metabolism shuts down, can last for years, decades, or even up to a century — can recover in as little as 10 minutes when water is added this makes them industrially useful - used to feed other organisms

Answer 4

can be sessile or free swimming by movable ‘scales’ - can swim well

Answer 5

ciliated corona (suspension feeding) predatory in some species

Answer 6

sexually (mictic and amictic)

Answer 7

dont have one trait that consistently runs thru all molluscs bc of such diversity look for 4 things: (basic body plan of molluscs) shell, mantle, foot, gills

Answer 8

Conchifera: all shell bearing molluscs Aculifera: no SOLID shell, only spicule or sclerite bearing

Answer 9

- calcium carbonate shell w 8 pieces and shell valves - ciliated gills (ctenidia) - osphradia (sensory organs) - mantle cavity - shell attached muscles - radula - pericardium and gonads - circulatory system w heart and dorsal blood vessel but then it is open

Answer 10

- head - visceral mass - muscular foot (hydrostatic) - mantle (pallium) - gills (ciliated ctenidia)

Answer 11

- radula - well developed digestive system

Answer 12

radula and shell valves

Answer 13

slow moving never detached from substrate

Answer 14

visceropallium: all collective dorsal parts (includes body organs and shell) cephalopodium: all collective ventral parts (includes head -mostly mouth- and foot)

Answer 15

radula w magnetite teeth (rasping and feeding) ctenidia - cilia create water flow to increase ability to take gases out of water

Answer 16

broadcast sperm and females retain eggs and then they are fertilized

Answer 17

from head w mouth to anus anterior to posterior — from ciliated water flow clears waste — exhausted near the anus but not thru the anus runs past paired osphradia (sensory) - olfactory or chemosensory epithelian areas near gills

Answer 18

diagnostic trait magnetite (Fe3O4 : loadstone) makes radular teeth very hard for scraping rock substrates can bind these minerals to teeth to make them harder - 3 fold harder than human enamel shows up on rocks in “fan pattern”

Answer 19

basic nerve plan for molluscs - related to annelids — 2 pedal nerve cords then split into 2 areas - these 2 areas correspond to 2 body areas (visceropallium and cephalopodium) pedal nerve cords on bottom (cephalopodium) visceropallium nerve cords on top ring of nerve tracks that surround pharynx BRAIN SURROUNDS ESOPHAGUS

Answer 20

coelom - principal body cavity in annelids, echinoderms, and chordates - fully lined w mesothelium hemocoel - principal body cavity in arthropods and molluscs (not annelids) - with reduced form of coelom BOTH: structures filled w fluid and act as cushion or hydrostatic skeleton, protecting organs

Answer 21

Pericardium space with muscular heart is confined to just the posterior end Blood goes anteriorly via dorsal blood vessel Blood enters the connective tissue spaces directly, surrounding the organs in the hemocoel Blood percolates eventually into the afferent blood vessel of the ctenidia, and is then returned to the heart circulation looles familiar - heart in same position - no ventral blood vessel (not returning in single vessel be the blood is coming back thru the coelomic space = hemocoel - blood entering connective tissue space directly that are surrounding organs - eventually comes back thru other vessel and denidia then back to heart

Answer 22

Digestive glands (pair) secrete digestive enzymes and store lipid energy Anterior has characteristic radula, formed in deep invagination ventral to buccal cavity, secretes ribbon of teeth now we see radula - vegetative matter that the mollusc consumes - posterior side to the right - head here is just mouth in polyplacophorans radula = constantly regenerated - teeth in radula sac -to provide grinding motion sac is secreting hard radula - represents feature that we didnt have in annelids at all Present in all extant molluscs except bivalves

Answer 23

light sensing thru multiple lenses and openings on the back — called ocelli can detect movement and shapes made of CaCO3 Essential for sensing light regimes, hence nocturnal behavior patterns — need to know when light and dark for feeding

Answer 24

- shell as protective retreat — long coiled cone (chitinous operculum - hard door that seals them in) - torsion in body plan (both internally and externally) - development of head with tentacles and eye spots

Answer 25

bilateral symmetry

Answer 26

- downside of torsion is fouling of ctenidia — solved by loss of right ctenidium - shift of anus to right side - osphridium to left and oblique current over ctenidium through mantle cavity and out hole vent in shell

Answer 27

torsion - (twisted shape, not elongated like Poly- and Monoplacophorans, cephalopodium 180o from visceropallium, mantle cavity over back of head, anus opens into anterior mantle pocket, gill(s) in this anterior cavity) evidence = cross-over of visceropallial nerve cords

Answer 28

scaly-foot or volcano snail - A remarkable deepsea gastropod, with metallic armour and symbiotic feeding — just discovered and already under conservation — International conservation bodies are largely ineffective against national policies — Depth is no refuge from anthropogenic impact queen conch - as they get older and reach maturity, this is when highest reproductive output. conservation and current policies only for length but should be for shell thickness at flare abalone - density matters, if not enough wont support the population due to being broadcast spawners — population continues to fail even after stopping fishing bc of alee effect — positive correlation between population size or density and the mean individual fitness of a population or species, usually at low populations —POSSIBLE CAUSES OF REPRODUCTIVE FAILURE: - Fertilization failure due to spawning distance - Poorly provisioned trocophore larvae (malnutrition) - Competition with other benthic organisms, and starvation - Environmental stress

Answer 29

radula, proboscis is everted for grazing, moon snails drill into bivalves and eat them, cone snails use conotoxins, injected via proboscis to stab fish and immobilize them

Answer 30

internal sexual reproduction

Answer 31

- new muscle arrangements for shell contraction – adductor muscle - evolution of hinge on bivalve shell - muscular arrangements for burrowing - shell secretion system - compared to polyplacophorans these are now bent over to close up (example of evolutionary change) - Enlarged singular muscle here where in polyplacophorans there were 8 pairs of muscles

Answer 32

NO radula laterally compressed body (opposed to horizontally)

Answer 33

shell hinges (ligaments) keep it open, muscles close it

Answer 34

- laterally compressed body (opposed to horizontally) - deep mantle cavity - single pair of ctenidia - new muscle for shell contraction (adductor muscle) - dorsal hinge for shell open and close - retaining nerve ring and dual cord structure but minimal external cephalization —In many species: dual siphons (incurrent and excurrent siphon)

Answer 35

- adductor muscle - could also be dorsal hinge - NO radula

Answer 36

heat dome effects show drying out from osmotic stress or desiccation, leading to death (not snapping back like when cooked)

Answer 37

burrowers – deep and shallow, digging action w foot, 1. expansion of foot terminus creates anchor, 2. contraction of adductor muscle closes shell, 3. contraction of dorso-ventral muscles pulls animal down into substrate Mussels – byssal threads hold onto substrate on exposed intertidal rocky shore

Answer 38

protobranchia = deposit feeding – using ciliated palp tentacles, each tentacle has a ciliated groove carrying particles back to mouth autobranchia = suspension/filter feeding – ctenidium used for gas exchange AND suspension feeding --> lateral cilia create water current, laterofrontal cilia intercept particles, frontal cilia carry particles down filament

Answer 39

hinge ligament very important – main defense mechanism bc it will snap shut when released from stretching

Answer 40

wood borers, septibranchia, fish parasites

Answer 41

- zooecium (exoskeleton or ‘house’) - operculum (protective door) - U-shaped digestive tract - 2 coelomic compartments (lophophoral coelom and perivisceral coelom)

Answer 42

no specialized organs (backtracking away from molluscs)

Answer 43

colonial bc polymorphism – non-feeding non-reproductive zooid for defense purposes only = avicularium (large operculum and strong muscles, no digestive tract) - brown bodies = not able to excrete accumulated metabolic waste so cells of the gut become storage spots for waste --> brown bodies where older zooids undergo senescence – defecate brown body and regenerate itself using stem cells – brown body ejected out

Answer 44

zooecium = exoskeleton (doesn’t join up which allows for passing of nutrients and for specialization) operculum = protective door (different structure than what we’ve seen before but same function) mesothelium lophophore and lophophore retractor muscles U-shaped gut (anus ejecting waste thru lophophoral sheath when tentacles extended) anus outside of exoskeleton when tentacles are extended

Answer 45

1. zooecium (house) exoskeleton – often calcified 2. lophophoral coelom (comprised of the hollow tentacles

Answer 46

colonial sessil

Answer 47

suspension feeders – lophophore (funnel w ciliated tentacles, goes up and brings stuff back in)

Answer 48

sexual and asexual, typically sequential androgynous hermaphrodites (male first then switch to female) broadcast spawners - most are “spermcasters” (only sperm released, eggs retained) sperm released thru pores in tentacular lophophoral coelom (tentacles filled w ciliated mesoderm) then ends w free-swimming ciliated larvae Note: this reproductive approach important for growing and expanding colonies

Answer 49

heterozooids (e.g. avicularia & vibracula) colonialism (defense against partial predation) calcification of frontal membrane (requires ascus) - hydrostatic ball w muscles can send out for defense

lecture midterm 2 Flashcards

(74 cards)