Arthropods/Echinoderms

Question 1

What are the key characteristics of echinoderms?

Answer 1

• endoskeleton
• tube feet
• no circulatory, respiratory, or excretory system
• nervous system but no brain

Question 2

Functions of the internal/external structures of a sea star

Answer 2

Ossicles - protective spines
Pedicellariae - protect and clean body surface
Skin gills - protect coelom lining; gases are exchanged
Eyespots - respond to light
Tentacles - respond to touch

Question 3

Describe an echinoderms water vascular system

Answer 3

• hydrostatic pressure permits movement
• feet contract, water enters and are able to suction onto surface of slippery rocks

Question 4

Distinguish between the 5 different classes of echinoderms and give an example of each

Answer 4

Crinoidea - sea lilies
Thick arms that extend from a central disk where organs penetrate into the arms

Asteroidea - starfish
Long, thin arms that are sharply bound from the central disk

Ophiuroidea - brittle stars
Strongest tendency toward 5-segment radial (pentaradial) symmetry

Echinoidea - sand dollars
Do not have arms, but are flattened with tube feet

Holothuroidea - sea cucumbers
Bilateral symmetry as adults

Question 5

What are 3 key characteristics of all arthropods and why are they important?

Answer 5

• Tough exoskeleton (protection, waterproof, adapts to environment)
• Series of jointed appendages (enable movement)
• Segmented body

Question 6

What structures do arthropods use for feeding?

Answer 6

Three pairs of appendages that are used as mouthparts. Specifically mandibles and palps

Question 7

What structures do arthropods use for respiration?

Answer 7

gills, lungs, tracheal tubes

Question 8

Describe the circulatory system of arthropods

Answer 8

• open circulatory system
• blood leaves vessels and moves through sinuses

Question 9

How do arthropods excrete wastes?

Answer 9

• using a set of Malpighian tubules
• using small excretory glands
• aquatic arthropods dispose of cellular wastes by diffusing them

Question 10

Describe the vision system of arthropods

Answer 10

Have compound eyes that contain more than 2000 separate lenses that can detect color and motion

Question 11

Describe how arthropods hear

Answer 11

They use tympanal organs. When sound enters the tympanal organ, it vibrates which then produces that sound.

Question 12

How do pheromones work?

Answer 12

A pheromone is a specific chemical that insects and other organisms use to communicate with others of the same species – usually those of the opposite sex. Once released, the pheromone travels through the air or water before reaching the second organism, which will often alter its behavior in response.

Question 13

How do arthropods reproduce?

Answer 13

Males and females produce sperm and eggs
- Fertilization takes place inside the body of the female
- The male uses a special reproductive organ to deposit sperm inside the female

Question 14

Distinguish between the 3 major groups of arthropods. (structurally and functionally)

Answer 14

INSECTS:
- 3 body segments (head, thorax, and abdomen)
- 3 sets of legs
- 1 pair of sensory antenna

ARACHNIDS:
- 2 body segments (cephalothorax and abdomen)
- 8 legs
- no antennae
- ocelli

CRUSTACEANS:
- 2 body segments (cephalothorax and abdomen)
- many have large claws
- walking legs and swimmerets
- antennae

Question 15

Compare/Contrast complete and incomplete metamorphosis

Answer 15

COMPLETE:
- egg to larva to pupa to adult

INCOMPLETE:
- egg to nymph to adult
- does not have fully developed wings