Blacktip Reef Shark
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Blacktip reef shark ( Carcharhinus melanopterus ) |
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| ( Quoy & Gaimard , 1824) |
The blacktip reef shark ( Carcharhinus melanopterus ) is a shark from the family of requiem or gray sharks.
Appearance
The blacktip reef shark is a medium-sized shark with a body length of 160 to around 200 centimeters. It has a broad and blunt snout, with the first dorsal fin beginning at the level of the end of the free inner edge of the pectoral fin. He has no interdorsal ridge .
Its basic color is gray to gray-brown, with its belly side being whitish. Its fins have differently pronounced black tips with a black border on the caudal fin. The first dorsal fin has a very distinctive black tip, which is clearly distinguished from the dorsal color by a whitish edge at the bottom. The extremely small second dorsal fin is located far back. The forked caudal fin is significantly longer in the upper part than in the lower part. It has five gill slits on each side just in front of the pectoral fins. Its upper jaw teeth are significantly wider than the lower jaw teeth. In addition, they are lightly sawed, while the lower jaw teeth are pointed. The eyes of the blacktip reef shark are very well developed. They have a reflective layer, the so-called tapetum cellulosum lucidum , which amplifies low residual light and allows the shark to see even in almost complete darkness. The lateral line organ is a sense organ for pressure stimuli, i.e. the sense of touch and hearing. The organ is located on the lateral line, at the level of the middle of the body and, in addition to the sense of sight, serves for orientation in the dark. The sense of smell is particularly well developed in the blacktip reef shark. The sense of smell enables you to register a drop of blood in a million liters of water. In the head area, this shark has so-called Lorenzini ampoules with which it can perceive weak electrical fields. The blacktip reef shark does not have a swim bladder like other fish. Such a swim bladder would regulate the buoyancy in the water. Instead, its very oily liver takes over this function. Blacktip reef sharks are very agile and fast swimmers.
Distribution area and way of life
The distribution area of the blacktip reef shark is the Indian Ocean , along the South African coast to the Red Sea and along the Indian coast. Furthermore, it occurs off Madagascar , the Seychelles and the Maldives , Thailand , Japan , the Philippines , Australia (excluding South Australia) and many island groups in the western Central Pacific .
In the eastern Mediterranean it occurs as a neozoon , into which it probably immigrated through the Suez Canal .
The blacktip reef shark prefers shallow water, mostly in the intertidal zone near the water surface, whereby the dorsal fin can protrude out of the water. However, it can also be found in water depths of up to 75 meters. Together with the whitetip and gray reef sharks , it is one of the most common species in the coral reefs of Oceania . The species can not only endure brackish water (Madagascar), but can also stay in fresh water (Malaysia) for a short time .
The latest studies have shown that adult blacktip reef sharks (and also other species) work together in their hunting grounds and maintain complex relationships with one another. They form organized groups with stable and long-term social ties to one another that can be compared to friendships. Here, gender and body size are decisive for the formation of a group within a local population. In addition, they can orientate themselves based on encounters with blacktip reef sharks they already know and recognize their territories. In terms of weight, the body-brain relationship roughly corresponds to that of mammals.
A blacktip reef shark can live to be around 35 to 40 years old.
Reproduction
The blacktip reef shark reaches sexual maturity with an average body length of 100 cm. He is one of the viviparous , so viviparous sharks. The actual mating takes place in a stomach-to-stomach position, mostly in the shallow water of their habitat. This leads to internal fertilization. The pregnancy depends on the area of distribution. In Australia, the wearing time is around nine months. In the Red Sea and the Mediterranean Sea, gestation lasts about 16 months. Usually two to six young animals are born, which are 35 to 55 cm long at birth. You are self-employed as soon as you are born. The mother no longer cares about her offspring.
food
Its diet usually consists of fish and invertebrates. Smaller shark and ray species are also hunted.
Meeting people
Due to the way of life, this species does not pose a very great risk to humans. Nevertheless, accidents are known, which, however, were probably provoked by inattentiveness and intrusiveness by people themselves. Although the animals are generally cautious and avoid people, they can also react aggressively to threats. Since they live in very shallow water, encounters can also occur while wading, for example in lagoons.
In the Red List of the IUCN (International Union for Conservation of Nature and Natural Resources) this species is listed in the "Lower Risk" category. The stocks are not acutely threatened with extinction, but they are endangered. The main reasons for this are, on the one hand, hunting and sport fishing (blacktip reef sharks are popular trophies), the destruction of their habitats (especially coral reefs) and water pollution .
literature
- Laith A. Jawad : Dangerous Fishes of the Eastern and Southern Arabian Peninsula , Springer 2018, ISBN 978-3-319-57924-5 , pp. 40-41
Individual evidence
- ^ Ralf Michael Hennemann: Haie & Rochen worldwide. Hamburg, 2001, year publisher, ISBN 3-86132-584-5 , p. 123
- ↑ Alberto Siliotti and others: Memofish Book - The fish of the Red Sea , Geodia Verlag Verona, 2002, ISBN 88-87177-43-0
Web links
- Blacktip Reef Shark on Fishbase.org (English)
- Blacktip reef shark in the hai.ch database
- The latest findings on blacktip reef sharks (including) compiled on the Project AWARE website
- Carcharhinus melanopterus inthe IUCN 2013 Red List of Threatened Species . Posted by: Heupel, M., 2005. Retrieved October 5, 2013.