CLASSIFICATION OF PENNATULA : SEA PEN
PHYLUM :- COELENTRATA OR CNIDARIA (Tissue grade, diploblastic and acoelomate. )
CLASS :- ANTHOZOA OR ACTINOZOA (Only polypoid generation. sedentary, solitary, colonial.)
SUB-CLASS :- OCTOCORALLIA (Polyps with 8 tentacles, bioluminescent.)
ORDER :- PENNATULACEA (Colony dimorphic with a long axial polyp and many lateral polyps.)
FAMILY :- PENNATULIDAE (Each leaf with single row of anthocodia. Highly evolved family.)
GENUS :- Pennatula (Sea pen)
It is found in the gulf of St. Lawrence to Carolina common in Europe and especially found in Newfoundland to Nornitueket
HABIT AND HABITAT
Pennatula is a sedentary and colonial actinozoan found in deep sea waters in sandy and muddy bottoms, 20 to 600 fathoms deep. It prefers warmer water
GENERAL CHARACTERSTICS OF PENNATULA : SEA PEN
- Commonly called as sea pen or sea feather.
- Animal is fleshy consisting of a very elongated primary axial polyp which gives numerous secondary bilateral polyps.
- Body is divided into a proximal stalk or peduncle devoid of anthocodia and distal rachis having secondary polyps
- Central axis or rachis posteriorly forms a peduncle with an end bulb.
- Anteriorly rachis bears lateral fleshy branches or pinnules containing a series of 8 to 12 gastrozooids or polyps. Each polyp has 8 pinnate tentacles.
- Each leaf has a single row or anthocodia of which the outermost one is the oldest and nearest the dorsal side and others are budded successively towards ventral side of the stem. The first polyp budded becomes the end polyp
- Skeleton comprises of a long horny unbranched axis supporting rachis only. Rachis is deep red. Peduncle is rose coloured. Base is whitish.
- Gastrozooids are feeding zooids, while siphonozooids draw water current. The siphonozooids have siphonoglyphs, which maintain water current in the canal system of the colony.
- Sexes are separate (dimorphic) and gametes develop in gastrozooids.
The animal contains rachis with lateral branches bearing polyps and all above characters and hence it is Pennatula.