Sea Star Anatomy and Behavior

Echinoderms, like sea stars, have unique structures and mechanisms. Their skeletons consist of bony platelets and a nerve ring instead of a brain. They move using hydraulically powered tube feet, which are inflated by water drawn through a sieve plate. This hydraulic system allows them to move in any direction. Sea stars feed by prying open shells with their tube feet and using their stomachs to digest prey externally.

What is the primary structural component beneath the skin of sea stars?

• Cartilage

• Bony platelets

• Fibrous tissue

• Silicon crystals

What allows sea stars to lock their arms in position for extended periods?

• A special protein

• Nerve impulses

• Hydraulic pressure

• Magnetic fields

What replaces the brain in echinoderms to coordinate arm movements?

• Nerve ring

• Central nerve cord

• Sensory nodes

• Ganglia clusters

How do sea stars inflate their tube feet?

• By drawing water through a sieve plate

• By absorbing nutrients

• By using muscle contractions

• By drawing air into the body

What is the function of the radial canals in sea stars?

• Forming a hydraulic system

• Transporting nutrients

• Conducting nerve signals

• Providing structural support

In which direction can sea stars move?

• Only forward

• Only backward

• In any direction

• Only sideways

What do sensory tube feet do during a sea star's movement?

• Measure temperature

• Sense water currents

• Search for gaps in prey defenses

• Detect light

How do sea stars begin their attack on prey?

• By using their teeth

• By releasing toxins

• By using hydraulic pressure to pry open shells

• By camouflaging

What unusual method do sea stars use to digest their prey?

• Using acid secretion

• Moving their stomach out of their body

• Swallowing whole

• Injecting digestive enzymes