Zoology Test 2d Flashcards Preview

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Flashcards in Zoology Test 2d Deck (40):
1

adaptive radiation

describes the evolution of many new species from common ancestor

2

mollusc origins

- originated in ocean, but now in almost every freshwater and terrestrial habitat
- very large phylum
- 50,000 extant species
- 35,000 extinct species

3

symmetry of mollusc

- bilaterally symmetrical
- some have secondarily derived asymmetry
- contains eucoelomate

4

general characteristics of mollusc

- muscular foot for crawling, burrowing and grasping
- visceral mass which contains internal organs
- mantle which secretes calcium carbonate shell
- soft unsegmented body

5

reproduction in mollusc

- most dioecious, some monoecious
- some have direct and some have indirect development

6

Development in mollusc

- mostly direct development
- larvae stage though is trocophore larvae

7

nervous system in mollusc

- several pairs of ganglia
- cerebral, pedal and visceral
-generally simpler than that found in anthropoids
- system of cephalopods is most advanced in any vertebrate

8

trocophore larvae

- found in annelids, platyhelminthes
- homology; indicate genetic relationship

9

cephalization in molluscs

- cephalopods and gastropods
- most others are grazers, scavengers or filter-feeders with little need for external cephalization
- usually have "foot"

10

excretory system in molluscs

- contain two nephridia

11

circulatory system in molluscs

- open system with pumping heart, blood vessels and blood sinuses whereby blood returns to heart
- cephalopods have closed system of arteries, capillaries and veins, complex with three hearts

12

respiratory system in molluscs

- most have gills derived from mantle tissue to increase efficiency of gas exchange
- incurrent and excurrent siphons present in bivalves

13

molluscs

- Monoplaophora
- Polyplacophora
- Scaphopoda
- Bivalvia
- Gastropod
- Cephalopod

14

Monoplaophora

- primitive mollusc
- found on ocean bottom known only as fossil
- exhibit pseudometamerism (segmentation)

15

Polyplacophora

- characterized by 8 dorsal plates
- found in intertidal zone of seacoasts
- feed by grazing on algae on rocks

16

Scaphopoda

commonly referred to as "tooth shells" or "tusk shells"

17

Bivalvia

- large, economically important class of mollusks
- highly adapted for burrowing
- filter-feeding
- clams, oysters, mussels, limpets, periwinkles, scallops
- restricted to aquatic environments
- most diverse in marine systems, but many freshwater

18

anatomy of bivalvia

- two shells connected by hinge ligament
- shell grows outward in "rings" from umbo
- foot extends anteriorly from shell to put animal forward
- adductor muscles pull shells together

19

respiration in bivalvia

- gills suspended from dorsal, interior surface of mantle cavity
- posterior incurrent and excurrent siphons create respiratory water flow

20

digestion in bivalvia

- gills also used for filter feeding
- mucus on gills traps food particles

21

reproduction in freshwater bivalve

- freshwater bivalve eggs fertilized internally in suprabrachial chamber above the gill
- eggs develop into glochidia larvae that parasitize a particular species of fish

22

reproduction in marine bivalve

- fertilization is external
- 2 larval stages
- one larval stage being the trochophore larvae

23

endangered bivalves

- dams and locks prevent fish migration so some can't reproduce because their host fish aren't present
- siltation and other forms of water pollution foul filter-feeding apparatus
- being overwhelmed by introduced mussels, which filter food
- poaching for pearl industry
- 184 of 300 native species are extinct, endangered or soon to be endangered

24

invasive bivalves

- zebra mussel (Dreissena polymorpha)
- Asian clam (Corbicula fluminea)

25

Is there a symbiotic relationship in certain bivalves? And if yes, what?

yes, mantle tissue contains photosynthetic zooxanthellae that provide much of clam's nutrients and color

26

pearls

produced by secreted fluid from the mantle called nacre that smooths out irritations (sand)

27

Gastropoda

- largest by far in terms of number of recognized species
- 70,000 living species

28

gastropod body plan

- torsion
- coiling
- lost organs, doesn't seem to bother them that they have lost organs
- radula

29

torsion

- is responsible for moving mantle cavity from back to front of body
- occurs before hatching
- space available in mantle cavity allows animals head to be withdrawn into shell for protection, foot forms barrier to outside

30

coiling

- spiral winding of visceral mass and shell
- original symmetrical arrangement gave way to conispiral shape, with shell to one side, which resulted in loss of gill on right side
- advantage: wastes expelled from right side of mantle instead of over head

31

radula

- rasping/grasping organ in mouth
- "teeth"
- modified for feeding, shell prying, harpooning and envenomating prey, chewing

32

reproduction in gastropod

- monoecious
- sperm exchange with internal fertilization
- some use dart to puncture mate
- eggs laid singly or attached to substrate
- larval stages occur before hatching
- hatchlings are miniature adults (direct development)

33

gastropod diversity

- nudibranchs
- sea hare
- conus (cone shell)

34

sea hare

marine gastropod squirts copious purple secretion from purple gland in mantle cavity when provoked

35

nudibranch

- nudibranchs feed on cnidarians and reuse undischarged nematocysts
- elaborate papillae covering their dorsal surfaces contain reused nematocysts

36

conus

- marine gastropod stings its prey to paralyze before consuming
- can kill other cone shells or humans

37

Cephalopods general characteristics

- nautilus
- octopus
- squid
- cuttlefish
- very derived molluscs but very ancient too
- most extinct forms had exterior shells
- active predators

38

advancements of cephalopods

- well-developed external cephalization and foot modified into series of tentacles and suckers
- completely closed circulatory system
- complex reproductive behavior

39

Cephalopod reproduction

- very sophisticated
- males undergo color displays directed against rival males
- sperm encased in spermatophores
- one modified tentacle used to pluck spermatophore from own mantle cavity and insert into mantle cavity of female

40

Cephalopod nervous system

- sophisticated nervous system
- sophisticated sensory organs
- tentacles with tactile and chemosensory cells
- mantle with chromatophores or bioluminescence for camouflage and communication
- intelligent with sophisticated behavior
- complex communication abilities
- contain eyes