1. Starfish or sea stars are echinoderms belonging to the class Asteroidea.[2] The names "starfish" and "sea star" essentially refer to members of the class Asteroidea. However, common usage frequently finds "starfish" and "sea star" also applied to ophiuroids which are correctly referred to as "brittle stars" or "basket stars".
There are about 1,800 living species of starfish that occur in all the world's oceans, including the Atlantic, Pacific, Indian as well as in the Arctic and theSouthern Ocean (i.e. Antarctic) regions. Starfish occur across a broad depth range from the intertidal to abyssal depths (>6000 m).
2. Jellyfish (also known as jellies or sea jellies or a stage of the life cycle of Medusozoa) are free-swimming members of the phylum Cnidaria. Medusa is another word for jellyfish, and refers to any free-swimming jellyfish life stages among animals in the phylum. Jellyfish have multiple morphologies that represent cnidarian classes including the Scyphozoa (over 200 species), Staurozoa (about 50 species), Cubozoa (about 20 species), and Hydrozoa (about 1000–1500 species that make jellyfish and many more that do not).[1][2]
Jellyfish are found in every ocean, from the surface to the deep sea. Some hydrozoan jellyfish, or hydromedusae, inhabit freshwater; freshwater jellyfish are less than an inch (2.5 cm) in diameter, are colorless and do not sting. Large, often colorful, jellyfish are common in coastal zones worldwide. Jellyfish have roamed the seas for at least 500 million years,[3] and possibly 700 million years or more, making them the oldest multi-organ animal.
3. Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp arefilter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important food source for larger animals from fish to whales. They have a high tolerance to toxins in polluted areas, and may contribute to high toxin levels in their predators. Together with prawns, shrimp are widely caught and farmed for human consumption.
4. Sharks are a group of fishes characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (or Selachii), and are the sister group to the rays. However, the term "shark" has also been used for extinct members of the suborder Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus. Under this broader definition, the earliest known sharks date from more than 420 million years ago.[1]
Since that time, sharks have diversified into over 400 species. They range in size from the small dwarf lanternshark (Etmopterus perryi), a deep seaspecies of only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (39 ft). Despite its size, the whale shark feeds only on plankton, squid, and small fish by filter feeding. Sharks are found in all seas and are common down to depths of 2,000 metres (6,600 ft). They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark that can survive in both seawater and freshwater.[2] They breathe through five to seven gill slits. Sharks have a covering ofdermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They also have several sets of replaceable teeth.[3]
Well-known species such as the great white shark, tiger shark, blue shark, mako shark, and the hammerhead shark are apex predators—organisms at the top of their underwater food chain. Their predatory skill fascinates and frightens humans, even though their survival is threatened by human-related activities.
5. Whale (origin Old English hwæl) is the common name for various marine mammals of the order Cetacea.[1] The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises,[2] which belong to suborder Odontoceti (toothed whales). This suborder also includes the sperm whale, killer whale, pilot whale, and beluga whale. The other Cetacean suborder Mysticeti (baleen whales) are filter feeders that eat small organisms caught by straining seawater through a comblike structure found in the mouth called baleen. This suborder includes the blue whale, the humpback whale, the bowhead whale and the minke whale. All Cetacea have forelimbs modified as fins, a tail with horizontal flukes, and nasal openings (blowholes) on top of the head.
Whales range in size from the blue whale, the largest animal known ever to have existed[3] at 30 m (98 ft) and 180 tonnes (180 long tons; 200 short tons), to various pygmy species, such as the pygmy sperm whale at 3.5 m (11 ft).
6. crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (Greek: βραχύς / brachys = short,[2] οὐρά /οura = tail[3]), or where the reduced abdomen is entirely hidden under the thorax. Many other animals with similar names – such as hermit crabs, king crabs,porcelain crabs, horseshoe crabs and crab lice – are not true crabs.
7. Sardines, or pilchards, are several types of small, oily fish related to herrings, family Clupeidae.[1] Sardines are named after the Mediterranean island ofSardinia, around which they were once abundant.[2]
The terms sardine and pilchard are not precise, and what is meant depends on the region. The United Kingdom's Sea Fish Industry Authority, for example, classifies sardines as young pilchards.[3] One criterion suggests fish shorter in length than 6 inches (15 cm) are sardines, and larger ones pilchards.[4] TheFAO/WHO Codex standard for canned sardines cites 21 species that may be classed as sardines;[5] FishBase, a comprehensive database of information about fish, calls at least six species "pilchard", over a dozen just "sardine", and many more with the two basic names qualified by various adjectives
8. Thunnus is a genus of ocean-dwelling fish in the family Scombridae, all of which are tuna, although other tuna species are found in other genera. The name of the genus is the Latinized form of the Greek θύννος, thýnnos, tuna, the word being first mentioned in Homer[citation needed]. Due to overfishing the genus range has been significantly reduced, being effectively removed from the Caspian Sea, for example.[2]
Their coloring, metallic blue on top and shimmering silver-white on the bottom, helps camouflage them from above and below.
They can grow to 15 feet long and weigh over 1,000 pounds. They can swim up to 50 miles per hour when pursuing prey
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