Category Zoology

            The giant squid is by far the largest invertebrate known. This monstrous creature lives in the ocean depths, and is only occasionally washed ashore. The specimens found so far have been 20 m in length, and their eyes are 40 cm across (these are the largest eyes known).

            Squids have tentacles like an octopus that surround a powerful beak. Two of these tentacles are enormously long, with gripping suckers at the end. The giant squid’s suckers have a ring of sharp teeth around them to help grip their prey. These suckers leave scars on the sperm whales that feed on them, and some of these scars are from suckers nearly three times bigger than those on the largest squid found so far. So there are much larger giant squids still to be discovered!

            Both starfish and sea urchins move about on tiny tube feet. These creatures have the same internal structure. Imagine the sea urchin as a starfish rolled up and joined along the edges of its arms.

            Coral reefs are built up from the skeletons deposited by millions of tiny invertebrate animals. These coral animals live only in warm water, feeding on plankton and also living on food substances produced by microscopic plants living inside their tissues. The reef builds up over thousands of years. Eventually the coral skeletons form complete islands that are colonized by plants and land animals.

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            The long arms that trail beneath the umbrella section of a jellyfish carry thousands of microscopic stinging cells. These cells have triggers, which cause the stinging cell to fire out a sharp thread when they are touched. The thread injects venom into any creature that contacts the stinging cells. Once the jellyfish’s tentacles have gripped the prey and the stings have immobilized it, the prey is drawn up to the jellyfish’s mouth and eaten.

Picture credit: google

            The octopus has been studied in the laboratory and has proved to be highly intelligent. Experiments have shown that the octopus can recognize shapes and colours, and can remember experiences. This means that it can be trained to some extent. The octopus also demonstrates its intelligence by escaping from captivity by climbing out of almost any tank in which it is kept.

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           Ribbon worms are marine worms that can grow as long as 30 m. they capture their prey by shooting out a spiked organ called a proboscis. It impales the prey so the worm can haul it in and eat it.

Picture credit: google