CLASSIFICATION OF TRYGON : STING RAY
Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present).
Group :- CRANIATA ( Cranium with brain present ).
Subphylum :- VERTEBRATA (Vertebral column present ).
Division :- GNATHOSTOMATA ( Jaws and paired appendages present ).
Super class :- PISCES (Paired fins , gills and skin with scales)
Class :- CHONDRICHTHYES { =ELASMOBRANCHI } (Endoskeleton cartilaginous. Scales usually placoid. spiral valve in intestine ).
Sub-class :- SELACHI (Sharks and rays. Gills in seperate clefts. Cloaca present).
Order :- HYPOTREMATA { = BATOIDAE } (Gills-slits ventral. spiracles present. dorsal fin on tail, if present)
Family :- RAJIDAE (Pectoral fin elongated and joined to sides of the body).
Genus :- TRYGON
GEOGRAPHICAL DISTRIBUTION
- Trygon : Sting Ray is abundantly distributed in tropical regions of the Atlantic and Pacific Oceans. It has been reported from India, Japan, China, North America, Australia and South America.
HABIT AND HABITAT
- Sting ray is found lying quietly on the sea bottom. It occasionally swims to change the place in search of prey or moves in self-defence. It is carnivorous feeding on small fish, crustaceans and molluscs. It also shows adaptive or protective colouration to conceal itself from the enemies.
GENERAL CHARACTERSTICS OF TRYGON : STING RAY
- Commonly called as sting ray or whip-tailed ray because of the presence of 3 stings or spines in tail. Spiny body divisible into head, trunk and tail.
- Sting Ray has huge kite-shaped fleshy body with rhombic disc shaped body and long whip like tail. Head and body dorsoventrally compressed.
- Outer anterior margin of pectoral fins cofluent with the sides of the head upto end of snout forming sub-rhombic disc-shaped, kite shaped fleshy body. Disc less than 1.3 times as broad as long.
- Paired pectoral fins being confluent with the sides of the head. Paired pelvic fins small. Dorsal fin modified as whip-like tail.
- Skin is smooth or spiny.
- Mouth is ventral and rectangular.
- Head contains a pair of dorsal eyes.
- When Sting Ray are inclined to move, most stingrays swim by undulating their bodies like a wave; others flap their sides like wings. The tail may also be used to maneuver in the water, but its primary purpose is protection.
- Sexually dimorphic. Male contains claspers near pelvic fin.
- The tail is especially elongated, whip like and contains 3 large mid-dorsal poisonous spine which are a modified dorsal fin. The poisonous spine is about 20 to 35 cm long and acts as organ of offence and defence.
- Spiracles present behind the eyes. Gill-slits 5 pairs, ventral in position.
- Viviparous. Long glandular filaments are formed in the uterine wall. During development of the embryo, the uterine filaments secrete a nutritive milky fluid which serves as food for embryo.
ECONOMIC IMPORTANCE
The fish is edible and its liver gives oil.
SPECIAL FEATURES
Caudal fin is small long and pointed. By poisonous sting it inflicts wound on the victim. The sting with poison gland produces ugly, slow-healing wound, sometimes complicated by gangrene or tetanus on bathers and fishermen.
IDENTIFICATION
Since this fish has whip-like tail and above features, hence it is Trygon or String Ray.
REFERENCES
- https://en.wikipedia.org/wiki/Stingray
- https://www.britannica.com/animal/stingray
- Book of Practical Zoology VERTEBRATE by S.S.LAL – Rastogi Publications.
- https://www.nationalgeographic.com/animals/fish/group/stingrays/
- SOURCES OF IMAGES – https://www.google.com/url?sa=i&url=https%3A%2F%2Fwinnipeg.ctvnews.ca%2Faggressive-mating-leads-to-animal-deaths-injuries-at-stingray-beach-exhibit-1.4483647&psig=AOvVaw2I_02Lw1-HGfO7fnhixxuj&ust=1602653097300000&source=images&cd=vfe&ved=2ahUKEwjb4uKV6rDsAhUtJLcAHXyID9QQr4kDegUIARCLAg
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fmyanimals.com%2Fanimals%2Fwild-animals-animals%2Ffish-wild-animals-animals%2Fspecies-of-stingray-and-their-characteristics%2F&psig=AOvVaw2I_02Lw1-HGfO7fnhixxuj&ust=1602653097300000&source=images&cd=vfe&ved=2ahUKEwjb4uKV6rDsAhUtJLcAHXyID9QQr4kDegUIARCPAg
- https://www.google.com/url?sa=i&url=https%3A%2F%2Fen.wiktionary.org%2Fwiki%2Fstingray&psig=AOvVaw2I_02Lw1-HGfO7fnhixxuj&ust=1602653097300000&source=images&cd=vfe&ved=2ahUKEwjb4uKV6rDsAhUtJLcAHXyID9QQr4kDegUIARDkAQ
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