Sharks are known as a species of fish characterized by a flexible connective tissue structure, pectoral fins that are not joined to the head, and five to seven individual openings seen as its gills lacking a single outer cover. Modern-day sharks are aptly recognized as descendants to the class of carnivorous fish known as Selachimorpha as well as the sister family of cartilaginous fish commonly known as rays.
The term “shark” has frequently been used to describe members of the subclass of Chondrichthyes known as Elasmobranchii seen as no longer extant including the genus of prehistoric sharks known as Xenacanthus and Cladoselache. Subject the this general classification, the earliest known sharks known today dates back to as far as over 400 million years ago.
Throughout this period sharks have branched out into more than 470 known species ranging from the little-known species of the dogfish shark in the Etmopteridae family known as the dwarf lanternshark 17 centimeters in length, to the slow moving filter feeding 41.5 foot shark known as the whale shark or Rhincodon typus.
Facts about Sharks
▪ The whale shark or Rhincodon typus since its origin 60 million years ago is recognized as the largest extant fish in the world today having a total length of between 39 to 41 feet and weighing at least 66,000 pounds rivaling many of the largest known dinosaurs in its weight and the sole member of the genus Rhincodon.
▪ Sharks are generally found in all open seas and are known to habitat at a standard ocean depth of about 200 meters or just over 6,500 feet.
▪ Generally sharks are not found in fresh water, nevertheless the bull shark also known as the Zambezi shark in Africa and the Nicaragua shark in Nicaragua have commonly been found to habitat in warm shallow water along costal regions and rivers. Not to be confused with the river shark, the bull shark recognized for its aggressive nature shows a preference for warm shallow water and can be easily found in brackish and freshwater systems such as rivers and estuaries. The river shark similar to the bull shark is also known to habitat fresh water systems, however the family is known for consisting of five rare species of shark in the order of Glyphis and have only been documented in parts of Australia as well as South and South east Asia.
▪ Sharks like other fish are known to extract oxygen from the water as it passes over their gill openings. However contrary to many other fish species, the shark gill slits are not covered, but rather exist in a sequence of rows often in numbers of five to seven slits behind the head.
▪ Rather than affixed to its jaw the shark’s teeth are embedded within the gums and constantly replaced during the lifetime. Some sharks throughout their life will lose up to 30,000 teeth at an average rate of sometimes once every 8 to 10 days to several months.
▪ The shark unlike the typical bony fish and terrestrial vertebrates does not possess a skeleton bone structure. Rather, like other cartilaginous fish such as rays and skates, the shark skeleton is made up of connective tissue and cartilage. Cartilage while known for its flexibility and durability as well as containing less than 50% the density of normal bone serves by reducing the total weight of the skeleton, effectively conserving energy.
▪ Nearly all sharks are seen as “cold blooded” or poikilothermic, signifying that the shark’s internal body temperature varies considerably to match that of their immediate environment. Conversely the short fin mako shark as well as the great white shark as members of the Lamnidae family of fast swimming sharks are homeothermic and are known to maintain a stable internal body temperature regardless of their ambient environment.
▪ The eyes of the shark are often comparable to other vertebrates as they are known for including a lens, retina and cornea, however their sight is effectively adapted to their marine environment with the support of a layer of tissue found behind the retina known as the tapetum lucidum. The shark like humans has the ability to dilate and contract its pupils, a characteristic shared by no other ray-finned fish and although they are known for having eyelids sharks do not blink as they use the surrounding water to cleanse their eyes.
▪ A sharks’s lifespan may vary according to the species, nonetheless most sharks are known to live for up to 30 years. The whale shark and the spiny dog fish shark however have been known to live up to more than 100 years.
▪ The average shark can swim up to a cruising speeds of 5 miles per hour, however when attacking or during feeding the shark can increase its speed to as much as 12 miles per hour. Notably the short fin mako shark can achieve a speed of up to 31 miles per hour.
California Academy of Sciences Shark Webcam
The California Academy of Sciences located in Golden Gate Park, San Francisco California committed in its research to inspire and educate is an excellent place for individuals to learn about shark species located across the world.
In its mission to explore, explain and sustain life the facility hosts a number of live webcams made available to online viewers including a high-definition Shark Lagoon Cam featuring the 18 known species of sharks, rays and bony fish located at the Shark Lagoon at the Academy.
View California Academy of Sciences Shark Webcam.
The National Aquarium Black Reef Exhibit Shark Webcam
Located in Baltimore, Maryland in the United States, the nonprofit aquatic education and conservation organization known as the National Aquarium is renown for its over 17,000 animals, including 750 species of birds, reptiles, mammals and fish housed within their award winning, naturalistic habitats.
Their new Black Reef man made coral-filled exhibit established in the heart of the Aquarium features a wide range of fascinating aquatic creatures ranging from their resident black tip reef sharks, honeycomb stingrays and even a five hundred pound green sea turtle.
View The National Aquarium Black Reef Exhibit Shark Webcam.