Echinoderm Form, Function and Locomotion Flashcards

1
Q

What does echinoderm mean?

A

Spiney skin

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2
Q

What are the 5 main living classes?

A

Asteroidea
Ophiuroidea
Echinoidea
Holothuroidea
Crinoidea

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3
Q

What are the common features of echinoderms?

A
  • No head or brain
  • Deuterostomes (blastophore forms anus then mouth)
  • Specialised gills for oxygen transport/gas exchange
  • Coelomate
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4
Q

Are echinoderms deuterostomes or protostomes?

A

Deuterostomes

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5
Q

Where are echinoderms found?

A

Marine - found from intertidal to deep waters. Mainly benthic living.

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6
Q

How many coelomic systems do echinoderms have?

A

4

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7
Q

What are the 4 coelomic systems of echinoderms?

A
  1. Perivisceral coelom - guts and gonads
  2. Haemal system - nutrient distribution?
  3. Peri-haemal system - nutrient distribution?
  4. Water vascular system (WVS)
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8
Q

What is the endoskeleton of echinoderms made up of?

A

Small calcareous plates called ossicles, bound together by catch collagen

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9
Q

What kind of symmetry do adult echinoderms show?

A

Radial pentamerous symmetry

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10
Q

How many arms do asteroidea usually have?

A

Usually 5 but can be over 40 (e.g. sunstars)

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11
Q

What animals are within Asteroidea?

A

Starfish or sea stars, sea daisies

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12
Q

What animals are within Ophiuroidea?

A

Brittle stars

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13
Q

What animals are within Echinoidea?

A

Sea urchins, sea biscuits, sand dollars

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14
Q

What animals are within Holothuroidea?

A

Sea cucumbers

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15
Q

What animals are within Crinoidea?

A

Sea lillies and feather stars

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16
Q

Where is the mouth of Asteroidea (starfish) located?

A

Underside

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17
Q

What is the name of the groove that runs down the arms of Asteroidea (starfish) and what is this surrounded by?

A

Ambilacral groove which is surrounded by tube feet (podia)

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18
Q

What do Asteroidea (starfish) have on the ends of their arms?

A

Sensory tentacles and eyespots

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19
Q

What do Asteroidea (starfish) have on their aboral surface?

A

Spines and pedicellariae

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20
Q

What are the respiratory structures of Asteroidea (starfish)?

A

Projections of coelomic cavity (Papulae) which bring oxygen to the peri-visceral coelom. Tube feet can also act as gills for oxygen transfer to the water vascular system (WVS) which opens to outside via madreporite

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21
Q

Where are Ophiuroidea (brittle stars) found?

A

Benthic, range of depths

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22
Q

How many arms do Ophiuroidea (brittle stars) generally have?

A

5

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23
Q

What do Ophiuroidea (brittle stars) lack, which Asteroidea (starfish) have?

A

Ambulacral grooves, papulae and pedicellariae

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24
Q

What do Ophiuroidea (brittle stars) use for locomotion?

A

Tube feet NOT primarily used
Arms propel animal forward
Articulated ossicles like vertebrae in arms aid flexibility

25
Q

What are ossicles?

A

Small calcareous plates bound together by catch collagen

26
Q

What are the respiratory structures of Ophiuroidea (brittle stars)?

A

5 pairs of in-foldings called bursae
WVS similar to Asteroidea - maderoporite on oral surface

27
Q

What are the two types of urchins within Echinoidea?

A

Regular and irregular urchins

28
Q

Explain what regular urchins are.

A

Sea urchins, radially symmetrical and hemispherical in shape with long spines

29
Q

Explain what irregular urchins are.

A

Hear urchins and sea dollars, bilaterally symmetrical and flatter with shorter spines

30
Q

What are the spines of Echinoidea connected by?

A

Ball and socket joint, moved by muscles

31
Q

What is used for locomotion in irregular urchins within Echinoidea?

A

Short spines

32
Q

What is used for locomotion in regular urchins (Echinoidea)?

A

Tube feet

33
Q

What are the respiratory structures in Echinoidea?

A

Peristomal gills around mouth which deliver oxygen to muscles and organs.
WVS similar to asteroids.
Tube feet also act as respiratory organs, delivering oxygen to WVS

34
Q

Do Echinoidea have pedicellariae?

A

Yes

35
Q

What do Holothuroidea (Sea cucumbers) look like?

A

Elongated from oral to aboral axis, bilaterally symmetrical

36
Q

What do Holothuroidea (sea cucumbers) use for locomotion?

A

Tube feet and muscular contraction

37
Q

What do Holothuroidea (sea cucumbers) lack in comparison to some other groups of Echinoderms?

A

Endoskeleton, ossicles greatly reduced
No spines or pedicellariae

38
Q

What structures are used for gas exchange in Holothuroidea (sea cucumbers)?

A

Buccal podia (modified tube feet), tube feet, respiratory tree in cloaca

39
Q

Where are Crinoidea (sea lilies and feather stars) found?

A

Lilies anchored to the substrate by stalk
Feather stars root-like cirri grasp substrate

40
Q

How many arms do Crinoidea (sea lilies and feather stars) normally have?

A

5-10 arms, subdivided into more arms each with jointed pinnules

41
Q

What do Crinoidea use for feeding?

A

Tube feet between pinnules

42
Q

What kind of symmetry do Crinoidea show?

A

Radial pentamerous symmetry

43
Q

Can Crinoidea (sea lilies and feather stars) move?

A

Sea lilies are sessile
Feather stars can move, but mainly sedentary

44
Q

How do feather stars move?

A

Alternating movement of arms allows short-distance swimming

45
Q

What are the gas exchange structures of Crinoidea?

A

WVS - no madreporite
Tube feet main site for gas exchange

46
Q

What are the functions of the spines of Echinoderms?

A

Protection and defence

47
Q

What is the structure of the spines of Echinoderms?

A

Made from rod shaped ossicles
There are primary (large) and secondary (small) spines
Spines can be moved in ball and socket type joint

48
Q

What spines do starfish and brittle stars tend to have?

A

Simple spines

49
Q

What kind of spines do urchins have?

A

Complex spines with a nerve ring, circular muscle and catch collagen.
Some spines are hollow and contain toxins - saponins

50
Q

In what Echinoderms are pedicellariae found?

A

Asteroids and echinoids

51
Q

What are the 4 main types of pedicellariae?

A

Tridactyl
Ophiocephalous
Trifoliate
Gemmiform

52
Q

What is the locomotory method of Crinoids (sea lilies and feather stars)?

A

Largely sedentary, some crawling/swimming

53
Q

What is the locomotory method of Ophiuroids (brittle stars)?

A

Crawl using arms

54
Q

What is the locomotory method of Holothuroids (sea cucumbers)?

A

Some burrow, others creep using tube feet on the sole

55
Q

What is the locomotory method of Echinoids (urchins)?

A

Regular urchins use tube feet and irregular urchins use spines

56
Q

Explain the movement of water in the water vascular system (WVS)?

A

Enters via the madreporite -> stone canal -> ring canal -> radial canal -> lateral canals -> ampullae and tube feet

57
Q

What is the water vascular system (WVS) lined with?

A

Cilia and muscle

58
Q

What muscles allow the movement of water in the WVS and enable movement, name them and the order in which they contract.

A
  1. Contraction of postural muscle
  2. Contraction of ampulla muscle move water to extend foot
  3. Contraction of retractor muscles on opposite side of foot
  4. Contraction of foot muscles to expel water back into ampulla