Question

Evisceration is found in
(a) Echinodermata
(b) Annelida
(c) Coelenterate
(d) Chordates

Answer 1

Evisceration is the removal of internal organs, especially those in the abdominal cavity. The term may also refer to the rejection of viscera as a defensive action by an animal. The process of evisceration is found among certain marine animals. Organisms like sea cucumbers are known to discharge the parts of internal organs when threatened. The discharged organs and tissues regenerate after a course of time.

Complete step by step answer:
Evisceration is commonly found among members of the phylum Echinodermata. Members like sea cucumbers exhibit evisceration when they are threatened. The organs are regenerated in a few days. When stressed, the sea cucumber faces away from the attacker and contracts its body wall muscles. This causes the wall of the cloaca to tear and the anus to gape. During evisceration in some species, several parts of the respiratory tree may be expelled. Water from the respiratory tree is forced into these tubules causing rapid expansion and they elongate by up to 20 times their original length. They have great tensile strength and become sticky when they encounter an object. The adhesive is unique among marine invertebrates and a firm grip is obtained in under ten seconds. The mass of threads can entangle and immobilize potential predators such as small fish or crabs.

Additional Information:
- Echinoderms are the largest phyla having no freshwater and terrestrial members. All members are exclusively marine.
- Their body is covered with a spiny exoskeleton. They are triploblastic and radially symmetrical.
- Starfishes, sea cucumber, Holothuria are examples of echinoderms.
So, the correct answer is 'Echinodermata'.

Note:
- Echinoderms are well known for their well-developed water vascular system
- The water vascular system is a fluid-filled canal system used by echinoderms for locomotion, food and waste transportation, and respiration.
- The system is composed of canals connecting numerous tube feet. Tube feet participate in locomotion, gas exchange, feeding, attachment, and sensory reception.