Sharks Food
- Sharks and rays have a very varied diet. They are carnivores which means that they eat animals rather than plants and algae. Some sharks commonly eat bony fishes, crustaceans (crabs, lobsters, and other animals with an external skeleton), mollusks(snails, sea slugs, octopus and squids), and different types of worms.
- A shark’s diet is often determined by its habitat. For example, sharks that live out at sea (pelagic sharks) are more likely to eatfish and squid because that is all that is available.
- Sometimes sharks change their diet as they get older. The Great White Shark mainly eats fish when it is young but once it reaches maturity it consumes more marine mammals like seals and sea lions.
- Most sharks prefer live food but they will also consume carrion (dead fish and other animals) that they find on the sea floor.
- Just like filter feeding whales, there are a few sharks that live by filtering plankton from the water. The filter feeding sharks may consume phytoplankton (microscopic plants and algae) while hunting for more nourishing zooplankton (tiny animals and larvae that drifts around on the currents). Ironically, the Whale Shark which is the largest fish in the sea, lives on plankton which is one of the smallest animals. So does the second largest fish; the Basking Shark. Although these sharks have huge mouths, their throats are tiny and they are unable to eat anything larger than a grapefruit. Their teeth which are no longer needed for feeding, have become very small.
- The largest ray (the Manta Ray) is also a plankton feeder. It has a flexible projection on each side of its mouth called cephalic lobes that it uses to funnel plankton towards its mouth.
- Most rays eat small fishes and benthic invertebrates; crabs, snails, and worms etc. that live on or under the sand.
- Sometimes its possible to tell what type of food a shark eats by the shape of its teeth. Sharks that catch fast swimming fishes tend to have very pointed teeth that help them grasp the fish. Sharks that eat hard shelled animals have flattened teeth that form a plate to help them crush the creature’s shell like a nutcracker.
- Tiger Sharks have a reputation for eating anything. They have been found with all sorts of strange things in their stomachs from clothes to license plates. Tiger Sharks have very sharp serrated teeth that are strong enough to bite through the shells of marineturtles.
Sharks are different with other fishes
-
Sharks and rays do not have true bones like other fishes. They have cartilage instead which is lighter and much more elastic and allows them to bend in very tight circles.
-
Sharks do not have swim bladders. A swim bladder is a gas filled sack inside the body of bony fishes that allows them to stay still without sinking. Sharks compensate by having a very big liver that is filled with oil. Even so, sharks sink unless they keep swimming forward. The exception is the Sandtiger Shark which swallows air to make itself more buoyant.
-
A shark’s upper jaw is not fused to its skull like most animals. When a shark bites a large object, it is able to move its upper and lower jaw forward in order to take a bigger bite.
-
Unlike other fishes, sharks are able to replace their teeth constantly. New teeth grow from the inner surface of the jaw and rotate forward when the old teeth get worn out or lost during feeding.
-
Sharks and rays do not reproduce like other fishes. Most fish release clouds of sperm and eggs into the water column where they mix together. The fertilized eggs then float around until the fish larvae hatch and form schools of tiny fish. Male sharks have two organs called claspers attached to their anal fins. They insert one of these into the female shark’s cloaca (the entrance to the uterus) to transfer sperm (just like in mammals). Some sharks and rays incubate the eggs in their uteruses until the baby sharks are ready to be born. Other sharks and rays (i.e. skates) lay eggs and attach them to the reef.
-
Sharks have between 5 and 7 gill slits on each side of their body in front of their pectoral fins. Bony fishes only have one pair. Having many exposed gill slits probably helps transfer more oxygen into their blood faster which allows them to swim very fast when they need to.
-
Most shark’s skin is covered in small denticles instead of scales. Denticles are a lot like teeth. They have dentine in the centre and enamel on the surface. This makes shark’s skin very tough and abrasive like sandpaper. The shape and position of some shark’s denticles also helps reduce friction so that they can slip through the water easier.
-
Sharks have an extra sense that is able to detect tiny electric fields. They can use this to find food that is buried or to search for animals to eat in the dark or in turbid water.
-
Sharks and rays make up the sub-class of fishes called elasmobranches. This sub-class is part of a class of cartilaginous fishes called Chondrichthyes which also includes chimaeras (ratfishes).
saving loans at payday advance service
White Shark Trust
The South African based White Shark Trust is “a non-profit organization founded in 2002 to promote and conduct research, education and conservation projects on the endangered Great White Shark”
It is the brain child of Michael Scholl (founder and trustee) who has been conducting research on Great White Sharks since 1997.
The goals of the White Shark Trust are as follows:
-
To establish a fund in the Republic of South Africa for the purpose of receiving grants and donations from international sources as well as sources within the Republic of South Africa;
-
To manage and disburse such funds in the furtherance of the objectives of the Trust;
-
To promote dialogue between various research, conservation, education and Government bodies concerned with management, research, conservation and education concerning the Great White Sharks (Carcharodon carcharias);
-
To assist in providing relevant advice on the management of the Great White Sharks (Carcharodon carcharias);
-
To obtain the support for the objectives of the White Shark Trust from local residents living around concentration hotspots for the Great White Sharks (Carcharodon carcharias), including Mossel Bay, Dyer Island / Gansbaai and False Bay in particular;
-
To obtain the support for the objectives of the Trust from the established tourism industry involved with the Great White Sharks (Carcharodon carcharias) located at Mossel Bay, Dyer Island / Gansbaai and False Bay in particular;
-
To ensure that effective action is taken in all matters affecting the welfare and preservation of the Great White Sharks (Carcharodon carcharias);
-
To promote educational opportunities for the general public, schools and the tourism industry;
-
To conduct and support scientific research projects and field expeditions with regards to the Great White Sharks (Carcharodon carcharias).”
In connection with other like-minded South African organizations, the work of the White Shark Trust is of primary importance in order to better understand the critical role that White Sharks play in balancing the marine environment. Without their joint efforts we are unable to identify the need for better shark protection.
The Shark Safe Network
The Shark Safe Network provides a framework to combine and focus the efforts of committed individuals and shark conservation groups towards specific shark conservation campaigns. If you have a passion to protect sharks, Shark Safe Network helps you to get involved and make a difference – by participating in a current campaign or by launching your own campaign in your community.
Shark Safe Network provides the information, tools, raw materials and support. You provide the passion!!
The goal of every Shark Safe Network campaign is to reduce and ultimately eliminate wasteful and unsustainable activities and products that threaten sharks’ survival. Shark Safe Network invites and welcomes participation from any and all organizations and individuals, provided that all campaigns are conducted according the Shark Safe Network campaign principles.
And we always keep in mind that helping sharks = helping people. When you consider any of the issues that threaten sharks today, there is also a corresponding negative impact on humans and the planet.
Shark Safe Network is all about getting involved and doing something that counts. Join the Shark Safe Network and you will make a difference!
