Echinodermata Phylum Quiz

Phylum Echinodermata

• Known as "spiny skin" due to the presence of dermal ossicles.
• Members include various marine organisms like sea stars, sea urchins, and sea cucumbers.

Class Asteroidea

• Commonly referred to as sea stars.
• Exhibit a star-like shape with arms extending from a central disc.

Water-Vascular System

• A network of water-filled canals enabling movement, food capture, waste expulsion, and gas exchange.
• Critical for locomotion and feeding through tube feet.

Symmetry

• Echinoderms display pentaradial symmetry, allowing their bodies to be divided into five equal parts.
• This symmetry is prominent in their arm arrangement.

Tube Feet

• Extensions of the water-vascular system, crucial for movement and feeding.
• Function through hydraulic pressure provided by the water-vascular system.

Oral Features

• The mouth serves as the oral opening, located on the underside.
• Sensory tentacles are positioned at the tip of each arm, aiding in environmental interactions.

Digestive Structures

• The pyloric stomach connects to digestive glands in each arm, facilitating digestion.
• The cardiac stomach can be everted to digest prey externally, allowing nutrient absorption.

Anatomical Features

• Ambulacral groove is a channel along the oral surface where tube feet extend.
• Dermal ossicles contribute to the spiny exterior, while dermal branchia facilitate gas exchange.

Reproductive System

• Gonads are responsible for sexual characteristics and reproductive processes.
• Sea stars are dioecious with separate sexes, and fertilization occurs externally.

Sensory and Nervous System

• Eyespots at the ends of arms detect light changes, aiding navigation and behavior.
• Lateral canal directs water flow to the ring canal, part of the water-vascular system.

Locomotion and Feeding

• Movement is primarily achieved through the water-vascular system.
• Feeding involves swallowing prey whole or utilizing the cardiac stomach for external digestion.

Excretion

• Anus acts as the muscular opening for waste elimination, linked to the intestine preceding it.
• Ammonia diffuses out through dermal branchia, maintaining osmoregulation.