CLASSIFICATION OF APLYSIA

PHYLUM :- MOLLUSCA (Unsegmented bilaterally symmetrical and provided with visceral mass, foot and mantle. )

CLASS :- GASTROPODA (Head bearing tentacles, eyes and radula; visceral hump and shell coiled due to
torsion.)

SUB-CLASS :- EUTHYNEURA (Nerve loop not twisted in figure of 8.)

ORDER :- OPISTHOBRANCHIA (Gastropods with detorsion; gills posterior of heart; shell reduced or lacking)

SUB-ORDER :- TECTIBRANCHIA 

GENUS :- Aplysia (The sea hare)

GEOGRAPHICAL DISTRIBUTION

  • It is found in India, Asia, West Indies and on the Florida coast.

HABIT AND HABITAT

  • Aplysia is a marine gastropod found crawling among seaweeds. It has remarkable power of colour changes like the colour of the sunoundings. It inhabits upto a depth of 40 fathoms in uncontaminated water.

APLYSIA

GENERAL CHARACTERSTICS OF APLYSIA

  • Commonly called as sea hare.
  • Body of the animal is soft, slimy, fleshy and whitish or greenish in colour. Anterior end bears head and neck.
  • Animal is slug-like, with the anterior angles of the head extended into two large tentacular folds.
  • Besides anterior tentacular fords, there are pair of eyes and behind eyes another tentacular fold like structure called as rhinophores.
  • Mantle cavity is open on the right side with backwardly pointing ctenidium through a longitudinal slit. Anus is posteriorly located. Opening of shell sac and seminal groove is also seen. 
  • Foot is muscular, and elongated pointed posteriorly
  • On the lateral side, there is a pair of large fleshy outgrowths called as parapodia, which project upwards and inwards to enclose visceral hump and are used as fins for swimming. 
  • Shell is internal and rudimentary. Opening of shell sac and spermatic seminal groove also seen. 
  • Animal is bisexual with a single gonoduct and a common genital opening.
APLYSIA

SPECIAL FEATURES

  • Aplysia when disturbed secretes a purple fluid from the opening shell sac found in the mantle wall and it makes itself invisible to the enemy.

IDENTIFICATION

  • The animal has rhinophores and all above features, hence it is Aplysia.

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