Sharks - Squaliformes2013
By Amelia Meyer
By Amelia Meyer
The group called Squaliformes is made up of approximately 80 species of sharks divided into several different families. This is one of the most varied and diverse groups. Its members are both tiny and huge and can be found in a wide range of ocean depths. Unfortunately, they are hunted by the most vicious predator of all, the human being, for their medicinal properties as well as for food.
The Dwarf Lanternshark is generally considered to be the world’s smallest shark.
The female of the species, which is slightly larger than the male, measures only about 19 centimetres at maturity. The largest squaloid is the Greenland Shark, which can reach about 6.4 metres and possibly even up to about 7.3 metres. This shark is known as a fearsome predator that has even nabbed terrestrial animals, such as reindeer, when given the opportunity. They are also scavengers. Most shark species will seldom vary their diet, sticking to one type of prey. Squaloids, however, are likely to chomp on what is available.
Squaliformes have five pairs of gill arches and slits and two dorsal fins. They do not possess an anal fin. Interestingly, many Squaliformes are bioluminescent (that is, they glow to varying degrees). Squaliformes live only in the saltwater of the oceans and are not able to survive in freshwater environments.
Many tend to stick to the bottom of the ocean. In fact, squaloids are known for achieving the greatest depths. An example is the Portuguese Shark, which was found at 3675 metres below the surface of the water. While this is considerably deeper than most, squaloids can usually be found below 400 metres down. Many of the species that stay at the bottom of the ocean have been known to move up during the night time.
This group of sharks is ovoviviparous. This means that eggs are fertilised inside the female’s body, where they hatch. They are then fed off the remaining egg yolk and nutrients in the oviduct until the young are ready to be born alive. They immediately live a life of independence and, therefore, need to be born with a full set of teeth and efficient hunting instincts.
There are several families in which many more individual species are represented. Each family presents with slightly different characteristics.
These families are the Dogfish Sharks (20 species), Gulper Sharks (15 species), Lantern Sharks (51 species), Angular Roughsharks (five species), Sleeper Sharks (18 species) and the Kitefin Sharks (10 species).
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