Zoology Test 3b Flashcards Preview

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

What does Echinodermata literally mean?

A

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

2
Q

Echinodermata diversity

A
  • 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
Q

symmetry of echinoderms

A
  • 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
Q

nervous system in echinoderms

A
  • cephalization is reduced or absent in this group
  • nervous system is decentralized
  • no brain
5
Q

feeding habits of echinoderms

A
  • 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
Q

water vascular system in echinoderms

A
  • 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
Q

coelom in echinoderms

A
  • functions in circulation, respiration and excretion

- fluid circulated by cilia on peritoneum lining eucoelom

8
Q

excretion and gas exchange in echinoderms

A
  • done via papulae and tube feet which project out between ossicles
9
Q

endoskeleton of echinoderms

A
  • dermal ossicles: little bony plates under skin, joined by connective tissue
  • some project outward as spines
10
Q

pedicillariae

A
  • small pincers extending from skin
  • clean skin of debris, protect papular, may aid in foo capture
  • in sea stars and urchins only
11
Q

osmoregulation in echinoderms

A
  • no specialized structure
  • restricted to marine ecosystems
  • therefore at equilibrium all the time
12
Q

reproduction in echinoderms

A
  • mostly dioecious
  • autotomy is common
  • con regenerate complete organism with one arm and 1/5th of oral disc
13
Q

autotomy

A

means that they loose a leg….

14
Q

Crinoidea

A
  • original, oldest
  • only way to explain radial symmetry
  • sea lilies and feather stars
15
Q

characteristics of sea lilies and feather stars

A
  • 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
Q

Classes of Echinoderm

A
  • Crinoidea
  • Asteroidea
  • Echinoidea
  • Ophiuroidea
  • Holothuroidea
17
Q

types of Crinoidea

A
  • sea lily

- feather star

18
Q

types of Asteroidea

A
  • starfish or sea star
19
Q

types of Echinoidea

A
  • sea urchin

- sand dollar

20
Q

types of Ophiuroidea

A
  • brittle stars

- basket stars

21
Q

types of Holothuroidea

A

sea cucumbers

22
Q

feeding in Asteroidea

A
  • 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
Q

tube feet in Asteroidea

A
  • used for locomotion and gripping bivalve shells so that shells can be pulled open
24
Q

major body modifications in Echinoidea - sea urchins

A
  • 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
Q

feeding of Echinoidea

A
  • grazers: feed on algae, detritus or small particles of food, although some feed on larger prey
  • Aristotle’s lantern
26
Q

body modifications and feeding in Echinoidea - sand dollars

A
  • 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
Q

feeding in Ophiuroidea

A
  • abundant in ocean, often covering sea bottom
  • detritivores
  • feeding done via moveable jaws
28
Q

detritivores

A

feed on decaying matter and plankton

29
Q

how do brittle stars differ from sea stars?

A
  • 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
Q

papullae

A

peritoneum that sticks up through holes in ossicles

31
Q

how do Holothuroidea differ from other echinoderms?

A
  • 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
Q

feeding in Holothuroidea

A
  • 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
Q

protostome

A
  • 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
Q

mosaic embryo

A

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

35
Q

deuterostome

A
  • 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
Q

regulative embryo

A

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