Echinoderms

Question 1

Briefly describe echinoderms

Answer 1

Marine animals
Endoskeletons of large plates/small scattered ossicles
Water-vascular system
Pedicellariae
Papulae
Pentaradial symmetry in adults

Question 2

What are the 5 classes in phylum echinodermata?

Answer 2

Asteroidea
Crinoidea
Ophiroidea
Echinoidea
Holothuroidea

Question 3

Briefly describe class asteroidea

Answer 3

Sea stars
Bright coloured
Flat and flexible body with ciliated epidermis

Question 4

Describe asteroidea aboral surface

Answer 4

Central disc with radiating arms
madreporites
Anus- inconspicuous
This side is covered with spines that have pedicellariae at their base

Question 5

What is the process of respiration in Asteroidea

Answer 5

Respiratory gases/ammonia diffuse across the papulae and tube feet

Question 6

What are papulae in reference to asteroidea

Answer 6

Soft projections on their aboral surface lined with peritoneum

Question 7

Briefly descibe the oral surface of asteroidea

Answer 7

Contains mouth, ambulacrum, ambulacral groove- which is bordered with rows of tube feet (podia)

Question 8

Name and describe the 2 stomachs present in asteroidea

Answer 8

Cardia stomach - everted through mouth to digest food during feeding
Pyloric stomach - smaller stomach that connects to pyloric ceca in each arm via ducts

Question 9

Describe the endoskeleton of asteroidea

Answer 9

Mesodermal
Ossicles bound together by catch collagen
A meshwork of spaces filled with cells and fiber that penetrates the ossicles known as the stereom

Question 10

What is the relation between regeneration and autotomy?

Answer 10

Regeneration is what allows organisms to regenerate pieces of themselves, autotomy is the intentional casting off of limbs to evade predators

Question 11

Summarize asteroidea reproduction

Answer 11

Sexual is more common, separate sexes usually with external fertilization as the method
Asexual can exist, typically by making clones via regeneration abilities

Question 12

Briefly describe class ophiuroidea

Answer 12

Large group
Brittle stars and basket stars
very fragile

Question 13

What about the arms differs in sea stars vs brittle stars?

Answer 13

Brittle stars have their arms distinct from the central disc, and they are more brittle

Question 14

Where is the ophiuroidea madreporite located?

Answer 14

Oral surface

Question 15

What is different about the ophiuroidea tube feet?

Answer 15

They lack suckers and ampullae

Question 16

How do brittle stars move?

Answer 16

Arm movement, they move with a pair of arms

Question 17

How is waste expelled in ophiuroidea?

Answer 17

Through the mouth

Question 18

Where are organs stored in brittle stars?

Answer 18

The central disc

Question 19

What are bursae?

Answer 19

Fluid filled sacs that exist for gas exchange

Question 20

What are the differences between regular and irregular echinoids?

Answer 20

Regular - hemispherical shape, radial symmetry, long spines, sea urchins
Irregular - bilateral, with short spines - sand dollars and heart urchins