Portland Aquarium » Sharks http://www.portlandaquarium.net Just another Aquarium Sites site Mon, 20 Oct 2014 18:24:43 +0000 en-US hourly 1 http://wordpress.org/?v=3.9.2 Leopard Shark http://www.portlandaquarium.net/2014/08/18/leopard-shark/ http://www.portlandaquarium.net/2014/08/18/leopard-shark/#comments Mon, 18 Aug 2014 15:43:58 +0000 http://www.portlandaquarium.net/2014/08/18/leopard-shark/   Fun facts about our Leopard Shark: They have become protected in California and Oregon coasts so that they are not over fished. These types of sharks are most commonly found in sandy or muddy bays and estuaries near the bottom. It is rare to find them in size over 6 feet long. Leopard sharks […]

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Leopard Shark

 

Fun facts about our Leopard Shark:

They have become protected in California and Oregon coasts so that they are not over fished.

These types of sharks are most commonly found in sandy or muddy bays and estuaries near the bottom.

It is rare to find them in size over 6 feet long.

Leopard sharks have a very distinctive pattern when born and look similar to the mammals.

Leopard sharks are ovoviviparous, which means that the eggs hatch within the mother.

They are also known to produce up to 33 pups in a litter.

The Leopard Shark can be found at the Portland Aquarium along with Pyjama Sharks, Wobbegong Sharks and Bamboo Sharks.

 

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Sharks http://www.portlandaquarium.net/2012/07/05/sharks/ http://www.portlandaquarium.net/2012/07/05/sharks/#comments Thu, 05 Jul 2012 16:54:14 +0000 http://oregonaquarium.org/?p=46 Shark From Wikipedia, the free encyclopedia Sharks are a group of fish 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 (orSelachii), 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 […]

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Shark

From Wikipedia, the free encyclopedia
Grey reef shark
Sharks are a group of fish 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 (orSelachii), 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 sea species 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 planktonsquid, 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.   They breathe through five to seven gill slits. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. They also have several sets of replaceable teeth.

Well-known species such as the great white sharktiger sharkblue sharkmako shark, and the hammerhead sharkare 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.

Etymology

Until the 16th century,  sharks were known to mariners as “sea dogs”.   The etymology of the word “shark” is uncertain. One theory is that it derives from theYucatec Maya word xok, pronounced ‘shok’.  Evidence for this etymology comes from the OED, which notes the name “shark” first came into use after Sir John Hawkins‘ sailors exhibited one in London in 1569 and used the word “sharke” to refer to the large sharks of the Caribbean Sea.

An alternate etymology states that the original sense of the word was that of “predator, one who preys on others” from the German Schorck, a variant ofSchurke “villain, scoundrel” (cf. card sharkloan shark, etc.), which was later applied to the fish due to its predatory behaviour.

Anatomy

Drawing of a shark labeling major anatomical features, including mouth, snout, nostril, eye, spiracle, dorsal fin spine, caudal keel, clasper, labial furrows, gill openings, precaudal pit and fins: first and second dorsal, anal, pectoral, caudal and pelvic

General anatomical features of sharks

Teeth

The serrated teeth of a tiger shark, used for sawing through flesh

The teeth of tiger sharks are oblique and serrated to saw through flesh

Shark teeth are embedded in the gums rather than directly affixed to the jaw, and are constantly replaced throughout life. Multiple rows of replacement teeth grow in a groove on the inside of the jaw and steadily move forward in comparison to a conveyor belt; some sharks lose 30,000 or more teeth in their lifetime. The rate of tooth replacement varies from once every 8 to 10 days to several months. In most species, teeth are replaced one at a time as opposed to the simultaneous replacement of an entire row, which is observed in the cookiecutter shark.

Tooth shape depends on the shark’s diet: those that feed on mollusks and crustaceans have dense and flattened teeth used for crushing, those that feed on fish have needle-like teeth for gripping, and those that feed on larger prey such as mammals have pointed lower teeth for gripping and triangular upper teeth with serrated edges for cutting. The teeth of plankton-feeders such as the basking shark are small and non-functional.

Skeleton

Shark skeletons are very different from those of bony fish and terrestrial vertebrates. Sharks and other cartilaginous fish (skates and rays) have skeletons made of cartilage and connective tissue. Cartilage is flexible and durable, yet is about half the normal density of bone. This reduces the skeleton’s weight, saving energy.  Because sharks do not have rib cages, they can easily be crushed under their own weight on land.

Jaw

Jaws of sharks, like those of rays and skates, are not attached to the cranium. The jaw’s surface (in comparison to the shark’s vertebrae and gill arches) needs extra support due to its heavy exposure to physical stress and its need for strength. It has a layer of tiny hexagonal plates called “tesserae“, which are crystalblocks of calcium salts arranged as a mosaic.  This gives these areas much of the same strength found in the bony tissue found in other animals.

Generally sharks have only one layer of tesserae, but the jaws of large specimens, such as the bull sharktiger shark, and the great white shark, have two to three layers or more, depending on body size. The jaws of a large great white shark may have up to five layers.  In the rostrum (snout), the cartilage can be spongy and flexible to absorb the power of impacts.

Fins

Fin skeletons are elongated and supported with soft and unsegmented rays named ceratotrichia, filaments of elastic protein resembling the horny keratin in hairand feathers.  Most sharks have eight fins. Sharks can only drift away from objects directly in front of them because their fins do not allow them to move in the tail-first direction.

What is your favorite shark and why?

Also check out Portland Aquarium’s latest educational display features new sharks that are known as juvenile epaulette sharks, also known as “Walking Sharks.”

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