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Taxonomy and External Anatomy of a Dogfish Shark. Why is it called a spiny dogfish shark?. Dogfish because they turn their head side to side when they swim Spiny because they have spines near their fins . Taxonomy. K: Animalia P: Chordata SP: Vertebrata C: Condrichthyes
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Why is it called a spiny dogfish shark? • Dogfish because they turn their head side to side when they swim • Spiny because they have spines near their fins
Taxonomy • K: Animalia • P: Chordata • SP: Vertebrata • C: Condrichthyes • O: Squaliformes • F: Squalidae • G: Squalus • S: S. acanthius
300?? • Sharks have been around for over 300 million years • There are over 300 species of sharks
3 Regions • Head: broad, flattened • Trunk: fusiform in shape to help with locomotion • Tail: compressed laterally, principal organ of locomotion
External Features • Rostrum: pointed snout at the anterior end of the body, helps overcome water resistance • Nares: external nostrils, located on ventral surface of rostrum, used to detect odors in the water • Jaws: on underside of head, sharp pointed teeth in rows (replaceable),
External Features • Spiracle: modified gill slit, serves in water intake when jaws are grasping food • Eyes: immovable eyelid, can not focus on one object simultaneously • Lateral Line: extends from spiracle to tail, receptor for vibrations and pressure changes
External Features • Pectoral Fins: located ventrolaterally behind the gill slits, helps with manuvering and keeping shark horizontal in water • Pelvic fins: located ventrolaterally at the end of the trunk • Dorsal Fins: unpaired, located on the dorsomedial line, 1st behind pectoral fin other behind the pelvic line
External Features • Caudal fin: major part of tail, consists of dorsal lobe and ventral lobe of unequal size • Mouth: located subterminally • Teeth: modified placoid scales, arranged in rows, can be replaced
External Features • Endolymphatic Pores: lead to endolymphaticduct, used in equilibrium • Ampullae of Lorenzini: pores in the skin at the top and bottom of head • Functions: electrical potential; hydrostatic pressure, temp gradient, salinity gradient
External Features • Claspers: modified copulatory organs located on the edges of the pelvic fin in adult male sharks • Cloaca: common exit for the digestive, urinary and reproductive systems • Papilla: Males- urogenital papilla, exit for urine and sperm; Females-urinary papilla, exit for urine only
External Features • Abdominal Pore: located on the lateral edges of the cloaca, serves as outlets for excess coelomic fluid
SKIN • Placoid Scales: modifications of teeth, embedded in skin pointing caudally • Development is very similar to teeth in higher vertebrates, including humans http://1.bp.blogspot.com/_D6I3F3P3x_4/S9iyOaQ5N9I/AAAAAAAAAFg/6Jfa3MUF3L4/s400/placoid+scale.jpg