Echinoderms

Question 1

Characteristics of the phylum

Answer 1

5 part radial symmetry, spiny skin (calcium carbonate), water vascular system, tube feet.

Question 2

Water vascular system

Answer 2

Filled with fluid, does feeding, respirations, internal transport, excretion, and movement.

Question 3

Tube feet

Answer 3

Used for movement and feedings, each feet has a suction cup at the end.

Question 4

Feeding

Answer 4

Carnivores, filter feeders, herbivores.

Question 5

Carnivores

Answer 5

Uses tube feet to open shells, uses enzymes to digest prey.

Question 6

Herbivores

Answer 6

Uses jaw-like structures to scrape algae from rocks.

Question 6

Filter feeders

Answer 6

Uses tube feet to catch plankton

Question 7

Respiration

Answer 7

Thin wall surface on tube feet, primary respiratory surface. Also has skin gills (small outgrowths, respiration occurs).

Question 8

Internal transport

Answer 8

Oxygen food and wastes are carried by water vascular system, distribution of nutrients by digestive glands and fluid within body cavity.

Question 9

Excretion

Answer 9

Digestive wastes released as feces from anus, nitrogen containing wastes are excreted as ammonia through the tube feet.

Question 10

Response

Answer 10

Nervous system not highly developed, nerve ring around mouth and radial nerves in arms, clustered eyespots, they have sensory cells that detect light, gravity, an chemicals released by potential prey.

Question 11

Movement

Answer 11

Move using tube feet, mobility is determined by structure of exoskeleton, e.g sand dollars and sea urchins have movable spines attached to the endoskeleton, and sea stars and brittle stars have flexible joins that let them use their arms to move.

Question 12

Reproduction

Answer 12

External fertilization: sperm and eggs are shed into ocean where fertilization takes places, the arms of sea stars are filled with gametes. Some are hermaphrodites, can repair themselves via regeneration.

Question 13

Groups of Echinoderms

Answer 13

Roughly 7000 species, classes: sea urchins and sand dollars, brittle stars, sea cucumbers, sea stars, sea lilies and feather stars.

Question 14

Sea urchins and sand dollars

Answer 14

Have large solid plates that box their internal organs, are detritivores (feeds on organic matter of dead things) or grazers (algae). Defends by burrowing under sand or mud, wedging themselves in rocks, they also have sharp spines.

Question 15

Brittle stars

Answer 15

Uses speed for defense, sheds arms when attacked, detached arm keeps moving to distract predator, are filter feeders and detritivores.

Question 16

Sea cucumbers

Answer 16

Detritivores, move along sea floor sucking up organic matter.

Question 17

Sea stars

Answer 17

Moves by creeping, most are carnivores, can regenerate anything as long as still connected to a part of the central body.

Question 18

Sea lilies and feather stars

Answer 18

Filter feeders, live on coral reefs and use tube feet to catch floating plankton.