32. Starfish are the animals with radial symmetry, like a star. They live at the bottom of the seas and oceans, under rocks and coral reefs at depths ranging from 0.5 to 300 m. Some species live in deeper areas of the sea. They usually have five arms but there are also those whose number reaches up to 50. If a starfish loses one of the arms after a while it grows new ones. Starfish have gonads and stomach tabs in their arms. They are crawling slowly ( with an average speed of 5-15 cm per minute) looking for prey. They are sometimes difficult to see because they hide in the crevices and nooks of the rocks. They move along the seabed in any direction using feet. The Common Starfish is the most common and familiar starfish in the north-east Atlantic. It also appears in Indian Ocean and sometimes in the west parts of the Baltic Sea. It lives at the bottom of seas and oceans. This starfish mainly eats mollusks as clams and oysters, snails and fish. It has five arms and it is about 10-30 cm across. There were known some starfish which were about 52 cm across. It is usually red or orange, but there are some yellow, white, blue purple or green ones. It exists four to five years. It is really slow and it has average speed about 5-15 cm/min. It’s got great and very interesting skill: regeneration.
36. Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel(Scomberomorus maculatus), enter bays and can be caught near bridges and piers. Common features of mackerel are a slim, cylindrical shape (as opposed to the tunas which are deeper bodied) and numerous finlets on the dorsal and ventral sides behind the dorsal and anal fins. The scales are extremely small, if present. A female mackerel lays about one million eggs at a time.
39. Northern shrimp P. borealis lives at depths of 20–1,330 m (66–4,360 ft), usually on soft muddy bottoms, in waters with a temperature of 2–14 °C (36–57 °F). The distribution of the nominate subspecies P. b. borealis in the Atlantic ranges from New England, Canada's eastern seaboard (off Newfoundland and Labrador and eastern Baffin Island in Nunavut), southern and eastern Greenland, Iceland, Svalbard, Norway and the North Sea as far south as the English Channel. In the Pacific, P. b. eous is found from Japan, through the Sea of Okhotsk, across the Bering Strait, and as far south in North America as Washington state. In their 8 year lifespan,males can reach a length of 120 mm (4.7 in), while females can reach 165 mm (6.5 in) long. The shrimp are hermaphroditic. They start out male, but after year or two, their testicles turn to ovaries and they complete their lives as females. Shrimp alkaline phosphatase (SAP), an enzyme used in molecular biology, is obtained from Pandalus borealis . The species' carapace is a source of chitosan, a versatile chemical used for such different applications as treating bleeding wounds, filtering wine or improving the soil in organic farming.
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