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SHARKS: THE ANATOMY AND PHYSIOLOGY OF A PREDATORIAL MACHINE. Taxonomy . Kingdom – Animalia Phylum – Chordata Class – Chondrichthyes (sharks, skates, rays, sawfishes) Order – 8 orders ( Lamniformes (mackerel sharks)) Family – 30 families ( Lamnidae )
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Taxonomy • Kingdom – Animalia • Phylum – Chordata • Class – Chondrichthyes(sharks, skates, rays, sawfishes) • Order – 8 orders (Lamniformes (mackerel sharks)) • Family – 30 families (Lamnidae) • Genus – 50+ genuses (Charcharodon) • Species – 370-400+ species (carcharias) • List of species
Feeding • Most are carnivorous but some are filter feeders (whale sharks, basking sharks) • Tiger sharks are referred to as the “garbage guts” of the shark world • Contrary to popular belief, most sharks are picky about what they eat • Great whites choose only animals with blubber
Respiration • Most sharks have to keep moving to move water over their gills • Water enters the gill chambers through the mouth or spiracles and exits through the gill slits. • Blood in the gill filaments absorbs oxygen from the incoming water.
Circulation • 2-chambered heart • Blood flows from heart to gills to body tissues back to heart • Countercurrent heat exchange enables fast-moving sharks to be from 10 to 20 degrees warmer than the water around them
Senses • Hearing – have inner ear, attracted to low frequency sounds, can hear up to 0.6 miles • Vision – excellent, 10x more light sensitive than us, attracted to shiny and thrashing, can see 50 to 100 ft. • Taste – have taste buds, actually spit things out • Smell – excellent, function in only smell not breathing, can detect some chemicals as small as 1 part per billion • Feel – group of sensory cells along outside of body called the lateral line used to detect vibrations in the water • Electroreception – Ampullae of Lorenzinidetect electric fields given off by living creatures
Reproduction • Mating is rarely witnessed, male bites onto dorsal fin and internally fertilizes with clasper while over top of the female • Can be oviparous (horn, swell sharks), ovoviviparous (mako and sand tiger sharks), or viviparous (hammerhead sharks) • Gestation period is very long from 9 months up to 3 ½ years
Shark Attacks • You are more likely to be killed by stepping in a sand hole and having it collapse than you are by a shark • Tips to avoid attacks: • Don’t swim during low light periods • Stay in groups • Be knowledgeable about the area you swim/dive/surf in • If you find one, leave it alone • Avoid looking like prey • Sharks are attracted to: • Blood, splashing and loud noises, shiny colors • International Shark Attack File
Ecology and Human Uses • Pilot fish, remora, and others clean parasites like copepods and flatworms off sharks • Integral part of the food chain: • fishes, crustaceans, mollusks, marine mammals, and other sharks • Sharks, elephant seals, and killer whales have been known to eat sharks • Behavior researched mainly for avoiding attacks • 100 million sharks are killed every year by humans even though several species are endangered and illegal to kill • Humans use sharks for: • Research, recreation like fishing and viewing, and products like medicine, jewelry, tools, and mainly fin soup
Shark Facts • The 1st sharks appeared on Earth 400 million years ago well before the 1st dinosaur roamed the Earth • Avg. life span is 25 years • Sharks never stop growing • Largest shark = whale shark (50 ft. long) • Smallest shark = dwarf lanternshark (5-7 in. long) • Fastest shark = mako shark (30 mph) • Deepest diver = Portuguese shark (9,000 ft. or 1. 5 miles) • Longest migration = a blue shark traveled 3,740 miles • Only freshwater capable shark = bull shark (the Borneo river shark (Glyphis sp. B), the Irrawaddy river shark (Glyphissiamensis), the New Guinea river shark (Glyphis sp. C), the Ganges shark (Glyphisgangeticus), the Speartooth shark (Glyphisglyphis) • Highest note heard is 800 Hertz (or G above High C on the piano), so humans can hear many high sounds that sharks cannot • Lowest note heard is 10 Hertz (or 1.5 octaves below the lowest key on the piano). The lowest note a human can hear is 25 Hertz, so we miss out on some of the very low frequencies that sharks can detect
Man-eaters!!! • Great white shark • Tiger shark • Bull shark • Hammerhead shark • Mako shark • Oceanic whitetip shark • Reef sharks, lemon shark, blue shark, etc…
Vocabulary • Placoid scales (dermal denticles) = small outgrowths that cover the skin of a shark similar in structure to the teeth • Liver = organ for energy storage and buoyancy • Clasper = one of the modified, usually paired organs by which the male clasps the female during copulation • Lateral line = sensitive receptors that detect gentle currents and vibrations • Ampullae of Lorenzini= special sensing organs forming a network of jelly-filled canals that detect electrical fields in the water • Spiracle = provide oxygenated blood directly to the eye and brain through a separate blood vessel • Dorsal fin = fin on top that stabilizes and may provide protection • Pectoral fin = paired fins on the side that control steering and add lift as the shark swims • Caudal fin = locomotive limb at the end of a shark that propels it forward • Viviparous = live birth (get nutrients from mother not an egg) • Oviparous = eggs hatch outside the mother • Ovoviviparous = eggs hatch inside the mother then give live birth • Cloaca = opening shared by the genital organs, the urinary and intestinal tracts • Spiral valve = lower portion of the digestive tract that is internally twisted or coiled to increase the surface area, which increases nutrient absorption • Atrium = a large muscular chamber that serves as a one-way compartment for blood that is about to enter the ventricle • Ventricle = a thick-walled muscular chamber that pumps blood
