Marine Biology (2+1)

Method of collection

On rocky shores (faces), since, most of the animals and plants live attached to the surface, they can be easily seen and picked up. However, quite a lot of animals  hide between the rocks. In rock pools, on sandy beaches and mud flats, what is visible at first glance is but a small fraction of the total population, as much of it lives under stones or burrows into the ground.

Most of the animals in a rock pool can be collected by turning over stones. As this will disturb the animals,  the active fishes and prawns will move away to hide in cracks and the crabs will scuttle away, you can see the slowly wriggling brittle stars and worms or a contracting sea anemone. Remember always to turn the stone back to its original position, so that the sessile animals such as sponges, sea anemones, tube dwelling worms, hydroids and bryozoans are not exposed to the sun’s heat or to their enemies. Brittle stars, many worms and some sea slugs are very sensitive to handling and may break into pieces. Therefore gently slide them into a glass bottle or polythene bag containing sea water.

Animals on rock faces will require to be scraped off with some force; an old chisel or scalped is ideal for the purpose. Limpets should be suddenly wrenched off while they are relaxed; once they are disturbed and on their guard it is very difficult to prise them off.

Burrowing animals can be dug out with a shovel or small rake. Conservation of wild life in sea is as important as on land. Be content to watch the seashore life intently. If you must collect do not over do it. One specimen of each kind, if required as a museum specimen may be taken away but no more. If you desire to study it alive, remember that most people do not have the expertise to maintain marine animals alive for more than a day or two. It is best to return the animals to the seashore near the place where you collected them. It is worth remembering  that batch of students  go on the ramphage overtuning each and every stone they come across in the seashore not bothering to return to its original position thereby collecting vast number of each and every form of life they come across, only to throw them in dustbin at end of the day. Do not be one of them.

A rectangular hand net is suitable for catching fishes or even large crabs if you are worried about their claws hipping your fingers. Animals with sharp spines like sea urchins, spider crabs and lobsters should be handled carefully with blunt-tipped, forceps which are ideal for lifting up delicate and soft animals like worm and sea slugs. Remember that many animals are venomous or can inflict  a sting. Some of hydroid colories and jelly fish can give a sting. Spines of fish like sting ray, scorpion fish or catfish and of some sea urchins also contain venom. Any cutor wound should be immediately bathed with clean water and antiseptic applied on them.

The animals can be placed in polythene bags or glass bottles and larger ones in plastic buckets. Small and delicate animals such as sea slugs can best be kept in small vials. It is almost impossible to search for minute forms such as sea spiders, skeleton shrimps, amphipods and some worms directly on the seashore. It is best to bring back a colony of hydroids,  seaweeds or sponges and keep them in an enamel or glass tary or jar over night. By next day  lack of O₂ in the water will force these tiny animals to drop to the bottom from where they can be picked up.

Animals can be preserved in 4% formation prepared by diluting  it with sea water. or they may be washed with tap-water and preserved in 70% alcohol or methylated spirit. Storage of animals with limy shells (crustacean, Molluscs) for a long time in formalin dissolves the shell. They are best preserved in alcohol. Remember that formalin is very poisonous and also injurious to our eyes and skin.

Shorts are better than trousers for wading in shallow water. Many animals are most abundant and some animals like sea stars are only found at places which they are always submerged in water, even during spring low tides.. A cap or hat which can be secured against wind is essential in our climate. Shoes should be with laces; sandals and chappals have a disconnecting habit of ending up with broken straps. It is painful to walk barefooted in mud, for there are always shells with sharp edges and near cities even broken glass bottles. On rocks overgrown with barnacles thick soled shoes are a must.

Hunter boots are good for shore collection, as long as the treads  on the soles are not worn out. Smooth rubber, soles involve the risk of slipping and hurting oneself. The black rubberized composition on water proof shoes meant for wear in rainy season is ideal as the shoes grip rock firmly. On very slippery rocks in heavy surf, the three point contact method of moving is best i.e., always have either both hands and one foot, or one hand and both feet, in contact with rocks. On some shores with very flat slopes or high tidal range, the water at high tide can come rushing  faster than you can walk (you cannot run in uneven slippery rocks or in soft mud). Be careful to come out well in time before the incoming tide overtakes you or while collecting on a high patch of ground surrounded by low shore level, you may suddenly find yourself surrounded by water unless you are vigilant. when collections are done in evening, it is a good idea to have an electric torch for use, as it may become dark while you are still at some distance from dry, even land.

Many timid animals as well as contractile animals like sea anemones and corals are best seen while submerged . When the sea bottom is exposed, they are either hidden or appear as shapeless, blobs. The use of a  glass bottom boat  in shallow water enables one to see under water without getting wet. You can make a water glass by knocking off the bottom from an old bucket and replacing it with a round piece of glass. Mae it water tight. You can hold bucket so that its bottom is below the water surface and put your head into the bucket. Then you can not only see sea life but can also dive down in shallow waters to collect it.