Zoology Test 3b Flashcards Preview

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Flashcards in Zoology Test 3b Deck (36):
1

What does Echinodermata literally mean?

"spiny skin" - endoskeleton of dermal ossicles with projecting spines
- made of calcium carbonate

2

Echinodermata diversity

- not particularly large (in term of species) about 6000 living species
- very important to ecology and evolution
- abundant in marine ecosystems
- humans are more closely related to echinoderms than to any other invertebrate group

3

symmetry of echinoderms

- radially symmetrical
- but have larval echinoderms have bilateral symmetry
- tells us that radial symmetry is secondarily derived
- secondary radial symmetry; evolved from bilateral ancestor, but evolved back to radial

4

nervous system in echinoderms

- cephalization is reduced or absent in this group
- nervous system is decentralized
- no brain

5

feeding habits of echinoderms

- feed on small organic particles or algae, small prey
- some however are efficient predators despite lack of central nervous system and cephalization
- most are active, mobile animals

6

water vascular system in echinoderms

- unique organ to echinoderms
- tube feet for locomotion
- functions in respiration, locomotion and excretion
- water flow: madreporite to internal system of canals to ampulla and tube feet
- stone canal > ring canal > radial canal > lateral canal > ampulla > tube foot

7

coelom in echinoderms

- functions in circulation, respiration and excretion
- fluid circulated by cilia on peritoneum lining eucoelom

8

excretion and gas exchange in echinoderms

- done via papulae and tube feet which project out between ossicles

9

endoskeleton of echinoderms

- dermal ossicles: little bony plates under skin, joined by connective tissue
- some project outward as spines

10

pedicillariae

- small pincers extending from skin
- clean skin of debris, protect papular, may aid in foo capture
- in sea stars and urchins only

11

osmoregulation in echinoderms

- no specialized structure
- restricted to marine ecosystems
- therefore at equilibrium all the time

12

reproduction in echinoderms

- mostly dioecious
- autotomy is common
- con regenerate complete organism with one arm and 1/5th of oral disc

13

autotomy

means that they loose a leg....

14

Crinoidea

- original, oldest
- only way to explain radial symmetry
- sea lilies and feather stars

15

characteristics of sea lilies and feather stars

- both start out attached to substrate via stalk, and continue much of life sessile, but adult feather stars detach and can swim
- arms are tentacle-like with leathery skin and small branched and mucus for trapping and eating suspended phytoplankton

16

Classes of Echinoderm

- Crinoidea
- Asteroidea
- Echinoidea
- Ophiuroidea
- Holothuroidea

17

types of Crinoidea

- sea lily
- feather star

18

types of Asteroidea

- starfish or sea star

19

types of Echinoidea

- sea urchin
- sand dollar

20

types of Ophiuroidea

- brittle stars
- basket stars

21

types of Holothuroidea

sea cucumbers

22

feeding in Asteroidea

- predators: feed on crustaceans, polychaetes, small fish and other sea stars
- eversible stomach: insert cardiac stomach into open bivalve shell to digest and absorb soft parts

23

tube feet in Asteroidea

- used for locomotion and gripping bivalve shells so that shells can be pulled open

24

major body modifications in Echinoidea - sea urchins

- oral surface has expanded around to the aboral side
- fused dermal ossicles form rigid test with long, movable spines, tube feet and pedicellariae
- can live up to 200 yo

25

feeding of Echinoidea

- grazers: feed on algae, detritus or small particles of food, although some feed on larger prey
- Aristotle's lantern

26

body modifications and feeding in Echinoidea - sand dollars

- very small spines used to burrow just below sand
- fused dermal ossicles form rigid test, with tube feet, and pedicellariae
- organic particles settle on aboral surface, and cilia move them down to mouth

27

feeding in Ophiuroidea

- abundant in ocean, often covering sea bottom
- detritivores
- feeding done via moveable jaws

28

detritivores

feed on decaying matter and plankton

29

how do brittle stars differ from sea stars?

- locomotion by movable arms (no tube feet)
- incomplete digestive system
- no pedicellariae or papullae
- autotomy and regeneration even better developed than in sea stars - they lose arms easily and grow them back readily

30

papullae

peritoneum that sticks up through holes in ossicles

31

how do Holothuroidea differ from other echinoderms?

- greatly elongated on oral-aboral axis
- ossicles reduced so body is relatively soft, use a hydrostatic skeleton
- arrangement of tube feet modified for crawling

32

feeding in Holothuroidea

- feed by picking up food or trapping food on tentacles and stuffing them into mouth one by one
- to defend themselves, they expel parts of viscera which are sticky may contain toxins
- can "throw up" digestive system to distract predator while they get away - regenerates in 3 months

33

protostome

- Annelids, molluscs, arthropods
- blastula embryo, mouth forms first and then anus forms
- spiral cleavage occurs in development
- coeolom forms differently
- a mosaic embryo is formed

34

mosaic embryo

if a cell is taken away from the embryo, then that individual cell will die. needs entire embryo to survive

35

deuterostome

- echinoderms, hermichordates, chordates
- blastula embryo, anus forms first and then mouth forms
- radial cleavage occurs in development
- coeolom form differently
- a regulative embryo is formed

36

regulative embryo

if a cell is taken away, then that cell can continue to develop on its own without the embryo. forms its own embryo ----> twins