Creatures of the Neritic Zone

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Creatures of the Neritic Zone

Post  Ashley on Sun Mar 27, 2011 5:26 pm

Many creatures live in the Neritic Zone which is the shallow area of the ocean that extends above the Continental Shelf. Creatures like the herring, mackerel, bluefin tuna, capelin, lobster, loggerhead sea turtle, dolphin, and the Kemp’s ridley live in the Neritic Zone. ( I will provide more detailed descriptions for these creatures later.)

Herring



Herring fish belongs to the genus clupea and family clupeidae. This family is estimated to include around 200 species of fish. Herring fish are relatively small, silver colored fishes, which are abundantly found in the temperate waters of North Pacific and North Atlantic oceans. There are mainly two species of herring, Atlantic herring or Clupea harengus and Pacific herring or Clupea pallasii. However, the name herring is more commonly used to refer to Atlantic herring. All the 200 species of herrings that belong to family clupeidae have unique distinguishing characteristics. One such important feature is that they have a single dorsal fin with no lateral line. The dorsal fins do not contain spines unlike other fishes. A few species are found to have pointed scales. Herring fish are also characterized by a protruding lower jaw, that looks like the jaw of a bull dog. These beautiful silver colored fish have a small head and laterally flattened, slender and sleek body. The flashing silver color of their body helps to conceal them in the surrounding water. Though it provides protection to them against sea predators, the same feature helps humans to catch them. The tail of herring fish is usually bifurcated and looks like a fork. The most common species of herring, i.e. Atlantic herring can grow up to 18 inches in length, while the pacific herring grows to a length of about 15 inches. On the other hand, Baltic herring is comparatively smaller than its relatives and grows to a length of only 14 to 18 cm. The Atlantic herring usually weighs up to 1.5 pounds.Herring fish thrive on minute organisms like planktons, crustaceans and fish larvae. Phytoplanktons are the main source of food for the young ones, while the adults feed on zooplanktons, like copepods, pteropods and other small cruataceans, fish larvae, small fish and even small animals. One of the most interesting herring fish facts is, that they keep their mouths open while swimming and in the process filter the planktons, which pass through their gills.Herring fish are known to swim in groups, which is referred as schooling. While swimming in vast schools, they provide food to the large predators like whales, cod, sharks, tuna, dolphins, etc. Herring fish are also known as forage fish, as they are near the base of the food chain and hence, serve as the foods for the predators.

Mackerel



The Atlantic Mackerel is typically an open ocean fish with voracious feeding habits. They travel in schools that often contain thousands of fish. The swift swimming mackerel has a streamlined body and swims at high speeds for extended periods of time searching for food. All individuals within a specific school tend to be the same size. Since cruising speed increases significantly with age and size, scientists believe that conformity of body size within a specific school is necessary to allow all fish to maintain identical swimming speeds. Mackerel may grow as large as 7 1/2 pounds and have a maximum age of about 20 years. The mackerel is native to both sides of the Atlantic Ocean. On the US coast, it ranges along the continental shelf from Labrador south to Cape Hatteras, North Carolina. Most mackerel inhabit the inner half of the continental shelf with none straying beyond the shelf's outer edge. Although frequently found near the water's surface, they can also be found as far down as 600 feet.Young mackerel feed on microscopic copepods. As they grow, they feed on progressively larger prey. Adults will eat any fish smaller than themselves, feeding heavily upon small herring, sand lance and young mackerel. They also consume a variety of invertebrates such as copepods, crab larvae, squid and shrimp.

Bluefin Tuna



The Atlantic bluefin tuna is one of the largest, fastest, and most gorgeously colored of all the world’s fishes. Their torpedo-shaped, streamlined bodies are built for speed and endurance. Their coloring—metallic blue on top and shimmering silver-white on the bottom—helps camouflage them from above and below. And their voracious appetite and varied diet pushes their average size to a whopping 6.5 feet (2 meters) in length and 550 pounds (250 kilograms), although much larger specimens are not uncommon. Atlantic bluefins are warm-blooded, a rare trait among fish, and are comfortable in the cold waters off Newfoundland and Iceland, as well as the tropical waters of the Gulf of Mexico and the Mediterranean Sea, where they go each year to spawn. They are among the most ambitiously migratory of all fish, and some tagged specimens have been tracked swimming from North American to European waters several times a year. They are prized among sport fishers for their fight and speed, shooting through the water with their powerful, crescent-shaped tails up to 43 miles (70 kilometers) per hour. They can retract their dorsal and pectoral fins into slots to reduce drag. And some scientists think the series of “finlets” on their tails may even serve to reduce water turbulence. Bluefins attain their enormous size by gorging themselves almost constantly on smaller fish, crustaceans, squid, and eels. They will also filter-feed on zooplankton and other small organisms and have even been observed eating kelp.


Capelin



Capelin are members of the Osmeridae family of smelts. They are known as sparling in England. Capelin are slender translucent olive colored, small-scalled fish that grow to a maximum length of 25 cm (10 in). Capelin was once the primary food of cod in the North Atlantic. When the cod population diminished the capelin population increased drastically. In summer, it grazes on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat a great deal of krill and other crustaceans. Whales, seals, cod, squid, mackerel, beluga whales and seabirds all prey on capelin in particular during the spawning season of the capelin while it migrates southwards. In years with large quantities of herring in the Barents Sea, capelin seems to be heavily affected. Probably both food competition and herring feeding on capelin larvae lead to collapses in the capelin stock. Capelin is an important forage fish, and is essential as the key food of the Atlantic cod. The North-East Atlantic Cod and Capelin fisheries therefore are managed by a multi-species approach developed by the main resource owners Norway and Russia.


Lobster



Lobsters are invertebrates, members of the Class Crustacea of the Phylum Arthropoda. This class includes animals without backbones and with hard shells like crab, shrimp, crayfish, water fleas and wood lice.A male lobster is called a cock and a female a hen or chicken (when she weighs about 1 pound).There are two kinds of lobsters, the "true" lobster (also called American lobster) and the spiny lobster. The true lobster has claws on the first four legs, lacking in the spiny lobster. The spiny lobster has a pair of horns above the eyes, lacking in the true lobster. Spiny lobsters also have two large cream-colored spots on the top of the second segment of the tail.Small lobsters, less than 1.5 inches carapace (carapace length is measured from the rear of the eye socket to the rear of the main body shell), hide in and about sea weeds and rocky habitat that provide enough food and shelter from predators. Adolescent lobsters, 1.5 to 3.5 inches carapace, are found in coastal habitats and offshore areas. Adult lobsters inhabit deeper waters, but return seasonally to shallow warmer waters. Spiny lobsters inhabit tropical and subtropical waters of the Atlantic Ocean, Caribbean Sea and Gulf of Mexico.Lobster can have many different colors, including blue-green, blue, red, yellow, red-orange and white. Some lobsters come in two colors, having half of their shell one color and the other half another.Lobsters grow by molting, or shedding their shells. Before they shed the old shell, they will form a thin one underneath. When molting, they secrete enzymes that soften the shell and connective joints. The lobster will then struggle out of its old shell while simultaneously absorbing water which expands their body size. This process takes about 15 minutes. Each time they molt, they will increase their size about 20%.After molting, lobsters will eat voraciously. They often eat their old shell which will replenish the lost calcium and speed up the hardening of the new shell. It takes about 6 to 8 weeks before their new shell is hard enough for lobsters to be able to protect themselves against their natural enemies.A young, immature lobster (first 5-7 years) will molt about 25 times a year. An adult male lobster molts twice a year and an adult female lobster once a year, usually in the summer. When lobsters get older, they will molt only once every 3-4 years.The only way to gauge the exact age of a lobster would be by their shell. However, since lobsters shed their shells so often, it is impossible to determine their age. Knowledge of body size at age makes scientists believe that lobsters can attain a maximum age of 100 years. The normal life span is about 15 years. Lobsters can grow to be 3 feet long in overall body length.Lobsters usually hunt for food at night. They eat fish, crabs, clams, snails, sea stars, mussels and sea urchins. By nature, lobsters are not cannibalistic, except when held in crowded conditions.To escape from enemies, lobsters swim backwards by flipping their tail.The lobster's body has 19 parts, each covered by a section of the shell. The shell is thin and soft where the parts join, so lobsters can bend their body and move about.Lobsters eyes are compound eyes, consisting of hundreds of lenses joined together on the ends of pair of jointed organs called stalks. The four small antennae on the front of their heads are used to "smell" their food or chemicals in the water. The tiny sensory hairs along their legs are used to "taste" their food. Lobsters keep their antennae and eye stalks moving constantly to search for food and to watch for enemies.True lobsters have two very powerful claws. One claw is sharp and used for cutting, the other is bony and used for crushing. Lobsters that have their heavy ("crusher") claw on the right are considered "right-handed" and the others are "left-handed".Lobsters can lose claws, legs, eyes and antennae through accident or self-defense, but are able to regenerate them. Lobsters often fight with other lobsters for territory. If another lobster seizes their claw, they may drop their claw to escape. Sometimes, the more aggressive lobster will tear the claw of the opponent off. A lobster with a claw missing is called a cull.Lobsters have a sophisticated nervous system that allows it to sense actions that will cause it harm and feel pain. Lobsters don't have an autonomic nervous system that puts it into a state of shock when it is harmed. For this reason, they will feel pain until their nervous system is completely destroyed.



Loggerhead Sea Turtle




Loggerhead turtles are the most abundant of all the marine turtle species in U.S. waters. But persistent population declines due to pollution, shrimp trawling, and development in their nesting areas, among other factors, have kept this wide-ranging seagoer on the threatened species list since 1978.Their enormous range encompasses all but the most frigid waters of the world's oceans. They seem to prefer coastal habitats, but often frequent inland water bodies and will travel hundreds of miles out to sea.The largest of all hard-shelled turtles—leatherbacks are bigger but have soft shells—loggerheads have massive heads, strong jaws, and a reddish-brown shell, or carapace. Adult males reach about three feet (nearly one meter) in shell length and weigh about 250 pounds (113 kilograms), but large specimens of more than 1,000 pounds (454 kilograms) have been found.They are primarily carnivores, munching jellyfish, conchs, crabs, and even fish, but will eat seaweed and sargassum occasionally.Mature females will often return, sometimes over thousands of miles, to the beach where they hatched to lay their eggs. Worldwide population numbers are unknown, but scientists studying nesting populations are seeing marked decreases despite endangered species protections.


Bottlenose Dolphin



Bottlenose dolphins are well known as the intelligent and charismatic stars of many aquarium shows. Their curved mouths give the appearance of a friendly, permanent smile, and they can be trained to perform complex tricks.In the wild, these sleek swimmers can reach speeds of over 18 miles (30 kilometers) an hour. They surface often to breathe, doing so two or three times a minute. Bottlenose dolphins travel in social groups and communicate with each other by a complex system of squeaks and whistles. Schools have been known to come to the aid of an injured dolphin and help it to the surface.Bottlenose dolphins track their prey through the expert use of echolocation. They can make up to 1,000 clicking noises per second. These sounds travel underwater until they encounter objects, then bounce back to their dolphin senders, revealing the location, size, and shape of their target.When dolphins are feeding, that target is often a bottom-dwelling fish, though they also eat shrimp and squid. These clever animals are also sometimes spotted following fishing boats in hopes of dining on leftovers. Bottlenose dolphins are found in tropical oceans and other warm waters around the globe. They were once widely hunted for meat and oil (used for lamps and cooking), but today only limited dolphin fishing occurs. However, dolphins are threatened by commercial fishing for other species, like tuna, and can become mortally entangled in nets and other fishing equipment. All dolphins, including the bottlenose, are porpoises and are in fact mammals. Although some people use these names interchangeably, porpoises are actually a larger group that also includes animals like the orca and the beluga whale.


Kemp's ridley




The Kemp’s ridley turtle is the world’s most endangered sea turtle, and with a worldwide female nesting population roughly estimated at just 1,000 individuals, its survival truly hangs in the balance. Their perilous situation is attributed primarily to the over-harvesting of their eggs during the last century. And though their nesting grounds are protected and many commercial fishing fleets now use turtle excluder devices in their nets, these turtles have not been able to rebound.For this reason, their nesting processions, called arribadas, make for especially high drama. During an arribada, females take over entire portions of beaches, lugging their big bodies through the sand with their flippers until they find a satisfying spot to lay their eggs. Even more riveting is the later struggle to the ocean of each tiny, vulnerable hatchling. Beset by predators, hatchlings make this journey at night, breaking out of their shells using their caruncle, a single temporary tooth grown just for this purpose. Found primarily in the Gulf of Mexico, but also as far north as Nova Scotia, Kemp’s ridleys are among the smallest sea turtles, reaching only about 2 feet (65 centimeters) in shell length and weighing up to 100 pounds (45 kilograms). Their upper shell, or carapace, is a greenish-grey color, and their bellies are off-white to yellowish.They prefer shallow waters, where they dive to the bottom to feed on crabs, which are their favorite food, and other shellfish. They also eat jellyfish, and occasionally munch on seaweed and sargassum. They may live to be 50 years old.







Sources: http://answers.yahoo.com/question/index?qid=20071017091158AAXNLmu http://www.buzzle.com/articles/herring-fish-facts.html http://www.cptdave.com/atlantic-mackerel.html http://animals.nationalgeographic.com/animals/fish/bluefin-tuna/ http://www7.taosnet.com/platinum/data/species/capelin.html http://en.wikipedia.org/wiki/Capelin http://www.veganpeace.com/animal_facts/Lobsters.htm http://animals.nationalgeographic.com/animals/reptiles/loggerhead-sea-turtle/ http://animals.nationalgeographic.com/animals/mammals/bottlenose-dolphin/http://animals.nationalgeographic.com/animals/reptiles/kemps-ridley-sea-turtle/

Ashley

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By The Way:

Post  Ashley on Tue Mar 29, 2011 2:27 pm

By the way, just PM me if you want me to add more creatures to this topic or the one about the Midnight Zone creatures and I'll consider adding them. Thanks!

Ashley

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