1. Loligo is found in warm seas and in coastal shallow or deep waters. Animal metachromatic i.e. colour Changing habits. Commonly called as squid having dark grayish and reddish spots.
2. It has a cosmopolitan distribution found along the entire Pacific and Atlantic coast, China, India and the U.S.A.
3. Commonly called squid.
4. Body is fleshy, dorsoventrally flattened and differentiated into 3 regions (i) anterior head containing 10 oral arms and a pair of eyes with olfactory crest, (ii) middle, trunk or visceral hump, and (iii) Posterior region with lateral fins or parapodia. Parapodium is the contention of the mantle. Head and trunk region are separated by collar.
5. Each one of 8 oral arms contain four rows of pedicellate suckers ventrally.
6. Remaining 2 oral arms on each side contains six pairs of pedicellate suckers. These arms are used for capturing prey and are called hectocotylus arms.
7. In males one such arm is also modified as a copulatory organ. Oral arms are modifications of the foot.
8. After dissecting the animal, 2 ctenidia, 2 kidneys and 2 auricles are seen.
9. Shell, internal horny and non-chambered and is used in maintenance of natural buoyancy.
10. Ventral siphon is formed by the modification of foot
11. Sexes separate.
12. Eggs are deposited in long cylindrical jelly masses attached together at one end.
13. The animal ejects ink called as loligo ink in its defense. Loligo has food value. It is eaten by Chinese and Italians.
Source:
1. Practical Zoology Invertebrates by S.S.Lal. 2. A Manual of Practical Zoology Chordates by Dr. P.S. Verma.
