Biology of Chordata Vertebrates

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  • Topic: Green turtle, Shark, Leatherback turtle
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Whale Shark (Rhincodon typus)
Kingdom: AnimaliaPhylum: ChordataSubphylum: VertebrataClass: Chondrichthyes (cartilaginous fish)Subclass: Elasmobranchii (sharks and rays)Order: OrectolobiformesFamily: RhincodontidaeGenus: RhincodonSpecies: Rhincodon typus|

Integumentary system

Whale Shark (Rhincodon typus) has the toughest and thickest skin of all the animals in the world. It reaches up to 14 cm of thick; whale shark is pale on the underside and dark gray-brown color with white spots on the top. This can serve as a camouflage looking up or down the sea for shark’s preys (SRI, 2008). As all the other Chondrichtyes, Whale Shark skin is covered with little cartilaginous tooth-like structures, this are dermal placoid scales arranged to reduce the turbulence of water flowing along the body surface during swimming (Hickman, 2006).

Whale shark maintains internal salt concentrations lower than seawater by pumping salt out through rectal glands and kidneys. Sharks retain urea dissolved in their body fluids. They also produce Trimethylamine oxide (TMAO) use to protect their proteins from denaturation by urea waste products. Retention of this organic solutes in their body fluids makes their osmolality slightly hypertonic to sea water (Hickman, 2008)

Whale Sharks are ectothermic; this means that their body temperature is similar to the surroundings. They may regulate their body temperature by behavioral mechanism such as spending time in warmer surface water (Thumbs, 2012).

Musculo-Skeletal System
As mentioned, Whale Shark is an elasmobranch; the skeleton of this animal is made out of cartilage instead of bone. This along with the big liver filled with oil helps the shark to float easier an spend less energy on its movement (SRI, 2008). They also posses an pelvic fins supported by appendicular skeletons, dorsal fins, a medial caudal fin and a median anal fin. The heterocercal tail in sharks shows that the upturned tail axis tends to produce a thrust directed downwards behind the center of balance of the fish and thus gives a moment turning the head upwards. This is countered in two ways—by the rotation of the tail along its longitudinal axis during each lateral beat, and through the action of the ventral hypochordal lobe. The shape of the tail and the mode of action of the tail in all sharks so far considered reflects a balance between these three factors, in all of them the net effect being the production of a forward thrust from the tail that passes directly through the center of balance of the fish (Stewart, Keith and Simanek, Dan, 2012). Respiration System

Whale Shark possesses 5 pair of gill slits located on the side of their heads (SRI, 2008). Water must continually flow across the gill slits in order for the shark to breath; They do not have gill covers like bony fishes do, so whale shark need to continually swim for constant flow. When water passes over the gill, a system of very fine blood vessels takes up the oxygen from the water. Digestive System

Whale Shark is a filter feeder. As it swims with its mouth open, masses of water filled with prey enter to its mouth consisted of 5 large gill arches. After closing its mouth, shark uses specialized organs called gill rakers to filter the nourishment from the water. Basically anything that does not pass trough the gills is eaten. (SRI, 2008). Preys may include plankton, krill, small fish and even squid. This shark can process over 6000 liters of water each our. Urinary System

Urea and trimethylamine (TMAO) in their blood and tissues help to maintain their osmotic balance. They are without the usual urinary tract, so they concentrate urea in their blood and excrete it through their skin (Hickman, 2006). Reproductive System

According to the Shark research institute, Reproduction behavior is uncertain. In their article “Whale Shark FAQ” they state; “Only one pregnant female shark has ever been exanimated by scientist Dr. Jennifer V. Schmidt, Director of...
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