Echinoderm Form, Function and Locomotion

Question 1

What does echinoderm mean?

Answer 1

Spiney skin

Question 2

What are the 5 main living classes?

Answer 2

Asteroidea
Ophiuroidea
Echinoidea
Holothuroidea
Crinoidea

Question 3

What are the common features of echinoderms?

Answer 3

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

Question 4

Are echinoderms deuterostomes or protostomes?

Answer 4

Deuterostomes

Question 5

Where are echinoderms found?

Answer 5

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

Question 6

How many coelomic systems do echinoderms have?

Answer 6

4

Question 7

What are the 4 coelomic systems of echinoderms?

Answer 7

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

Question 8

What is the endoskeleton of echinoderms made up of?

Answer 8

Small calcareous plates called ossicles, bound together by catch collagen

Question 9

What kind of symmetry do adult echinoderms show?

Answer 9

Radial pentamerous symmetry

Question 10

How many arms do asteroidea usually have?

Answer 10

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

Question 11

What animals are within Asteroidea?

Answer 11

Starfish or sea stars, sea daisies

Question 12

What animals are within Ophiuroidea?

Answer 12

Brittle stars

Question 13

What animals are within Echinoidea?

Answer 13

Sea urchins, sea biscuits, sand dollars

Question 14

What animals are within Holothuroidea?

Answer 14

Sea cucumbers

Question 15

What animals are within Crinoidea?

Answer 15

Sea lillies and feather stars

Question 16

Where is the mouth of Asteroidea (starfish) located?

Answer 16

Underside

Question 17

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

Answer 17

Ambilacral groove which is surrounded by tube feet (podia)

Question 18

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

Answer 18

Sensory tentacles and eyespots

Question 19

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

Answer 19

Spines and pedicellariae

Question 20

What are the respiratory structures of Asteroidea (starfish)?

Answer 20

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

Question 21

Where are Ophiuroidea (brittle stars) found?

Answer 21

Benthic, range of depths

Question 22

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

Answer 22

5

Question 23

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

Answer 23

Ambulacral grooves, papulae and pedicellariae

Question 24

What do Ophiuroidea (brittle stars) use for locomotion?

Answer 24

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

Question 25

What are ossicles?

Answer 25

Small calcareous plates bound together by catch collagen

Question 26

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

Answer 26

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

Question 27

What are the two types of urchins within Echinoidea?

Answer 27

Regular and irregular urchins

Question 28

Explain what regular urchins are.

Answer 28

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

Question 29

Explain what irregular urchins are.

Answer 29

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

Question 30

What are the spines of Echinoidea connected by?

Answer 30

Ball and socket joint, moved by muscles

Question 31

What is used for locomotion in irregular urchins within Echinoidea?

Answer 31

Short spines

Question 32

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

Answer 32

Tube feet

Question 33

What are the respiratory structures in Echinoidea?

Answer 33

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

Question 34

Do Echinoidea have pedicellariae?

Answer 34

Yes

Question 35

What do Holothuroidea (Sea cucumbers) look like?

Answer 35

Elongated from oral to aboral axis, bilaterally symmetrical

Question 36

What do Holothuroidea (sea cucumbers) use for locomotion?

Answer 36

Tube feet and muscular contraction

Question 37

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

Answer 37

Endoskeleton, ossicles greatly reduced No spines or pedicellariae

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

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

Question 41

What do Crinoidea use for feeding?

Answer 41

Tube feet between pinnules

Question 42

What kind of symmetry do Crinoidea show?

Answer 42

Radial pentamerous symmetry

Question 43

Can Crinoidea (sea lilies and feather stars) move?

Answer 43

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

Question 44

How do feather stars move?

Answer 44

Alternating movement of arms allows short-distance swimming

Question 45

What are the gas exchange structures of Crinoidea?

Answer 45

WVS - no madreporite Tube feet main site for gas exchange

Question 46

What are the functions of the spines of Echinoderms?

Answer 46

Protection and defence

Question 47

What is the structure of the spines of Echinoderms?

Answer 47

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

Question 48

What spines do starfish and brittle stars tend to have?

Answer 48

Simple spines

Question 49

What kind of spines do urchins have?

Answer 49

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

Question 50

In what Echinoderms are pedicellariae found?

Answer 50

Asteroids and echinoids

Question 51

What are the 4 main types of pedicellariae?

Answer 51

Tridactyl Ophiocephalous Trifoliate Gemmiform

Question 52

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

Answer 52

Largely sedentary, some crawling/swimming

Question 53

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

Answer 53

Crawl using arms

Question 54

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

Answer 54

Some burrow, others creep using tube feet on the sole

Question 55

What is the locomotory method of Echinoids (urchins)?

Answer 55

Regular urchins use tube feet and irregular urchins use spines

Question 56

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

Answer 56

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

Question 57

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

Answer 57

Cilia and muscle

Question 58

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

Answer 58

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