Classification:

• Phylum-Coelenterata
• Class-Hydrozoa
• Order-Siphonophora
• Genus-Physalia

Comments:

1. 1.Physalia is a colonial hydroid commonly known as Portuguese man of war.
2. 2.Colony has a large pneumatophore or float which is brilliantly coloured as blue or orange.
3. 3.The float or pneumatophore is bladder-like,elongated and pointed at both the ends,6 to 12 cm long.
4. 4.The upper surface of the float is produced into the crest or sail.
5. 5.A gas gland present inside the float secretes a gas of a composition similar to air.
6. 6.It helps the animal in floating over the surface of water.
7. 7.The swimming bells or nectocalyces are absent.
8. 8.Colony exhibits remarkable polymorphism and the phenomenon of division of labor.
9. 9.Beneath the float are hanging down the three types of zooids and tentacles.
10. 10.Tentacles are large and bear stringing batteries or nematocysts to kill the large fishes and prey.

Source:

1. Practical Zoology Invertebrates by S.S.Lal. 2. A Manual of Practical Zoology Chordates by Dr. P.S. Verma.