Caribbean Reef Sharks Final Outline

This discussion topic submitted by Andrea Knoch ( at 10:54 am on 4/30/00. Additions were last made on Sunday, April 30, 2000.

Caribbean Reef Shark

History of Sharks
- all modern sharks were present between 25 and 5 million years ago.
- separated into 19 families
- 368 different types of sharks exist
- 68 types within the Caribbean
- sharks descended from Gnathostomata, jawed fish, group

Identification of Caribbean Reef Shark
- five factors for each species of shark
- set of fin size, teeth, weight, location, and liver oil proportions
- coloration is the LEAST consistent for identification
- coloration depends on environmental and dietary habits
- Caribbean Reef Shark not described until 1944
- eyes are relatively large
- Length of second dorsal is greater than height
- birth length of 38 inches to adult length of 8 feet
- olive-gray, and paler shades of yellow gray in skin color
- lives around coral reefs in the tropical western Atlantic
- Scientific Name - Carcharhinus Perezi
- Family Carcharhinidae
- noted for its habit of resting motionless on bottom
- have two dorsal fins, no spines, an anal fin, and five-gill slits on each side of head
- some sharksí live for almost a century,
- average life span is less than 25 years

- skeleton of flexible cartilage, reinforced with some mineral deposits
- beneficial to shark instead of bone because much less dense than true bone
- helps in buoyancy and flexibility

- skin is similar to that of man, because of its outer epidermis, which can regenerate itself, like our skin, and the second layer called the dermis
- epidermis is covered with scales called dermal denticles, which are like thousands of minute teeth
- dermal denticles are tiny scales that possess a root canal, bloods vessels and nerves
- gives a sandpaper texture
- VERY durable
- wide array of denticle sizes, can be in serried ranks, or may be spread randomly
- the denticles are rounded in some spaces or smooth and without points

- have an upper and lower eyelid with little movement
- can see 50 feet from source and are moderately far sighted
- maximum dilation and constriction take about a minute, much faster than humans
- since seawater absorbs most colors rapidly, vision and sensitivity to color my not be as important to sharks in detecting prey as their senses of smell and hearing

- shark swims with its mouth opens to allow water to enter
- throat blocked by muscular tissue, the water exits through the gill slits
- while water is rushing through the gills oxygen is extracted and absorbed into the blood
- at the same time carbon dioxide is released from the blood into the water

- tail plays major role in power for swimming
- provides for sudden changes of direction
- unlike most fish, sharks have no swim bladder
- sharks are denser than water
- must constantly be swimming to avoid sinking
- and provide constant stream of oxygenated water to gills
- sharkís liver also counteracts tendency to sink
- liver occupies 90% of body cavity
- has lighter than water oils which decreases density of body
- for these reasons some swim as far as 35,000 miles yearly
- color will change when swimming from deep to shallow water

- sound is a means of locating prey
- fish make lower sounds than what humans can hear
- sharks are extraordinarily sensitive to lower tones
- can hear 1000ís of yards from source
- have an internal ear on each side of their head
- lateral-line system extends along sides of head and body
- consists of fluid-filled sensory canals
- contain receptors sensitive to vibrations, pressure changes, waves and
movements in the water

- eggs of the female are internally fertilized
- process is through insertion of the males claspers in to the colaoca of the female
- males bite and harass females
- during the breeding season, females are seen with torn and scarred fins
- shape of the eggs will vary from rectangular to ovular
- eggs hatch in six to ten months
- young sharks released at size of 12 to 14 inches

- important tools in the ultimate identification of any shark
- are two types; incisors are for cutting and molars are for crushing
- several rows under the gum tissue
- transition from large to small is very gradual
- anchored by a root
- frequently loose and break teeth
- Replacement of the lower takes 8 days and upper 7 days
- individual shark may shed as many as 30,000 teeth during its lifetime

- extremely efficient when it comes to finding food
- can hear things that are thousands of yards away
- attracted to area by recent heavy rains, washing down dead animals
- consume food equal to 3-14 percent of body weight in one week
- eat sharks (little cannibalism), rays, bony fishes, crustaceans, and cephalopods

- stomach of a shark has form of a U
- intestines are not coiled, therefore relatively short
- food then travels quickly though the intestine
- slows down to when entering enlarged section of stomach

Reasons for Fear
- can sense one part mammal blood to 10 or even 100 million parts water
- detecting pray by seeing, smelling, hearing, feeling, touching, tasting, water vibrations, and electric fields
- are considered dangerous, but with fewer numbers of recorded attacks and far fewer fatalities, are gray reef shark, blacktip reef shark, and Caribbean reef shark
- unagressive when meet divers, but will retaliate vigorously if disturbed, speared, or provoked
- the youngest sharks, the smallest, are fearless
- even very small shark, two feet in length, can inflict dangerous wounds
- only a third of shark attacks occur in water deeper than 5 feet
- divers are most attacked when entering and exiting the water
- sharks never attack a diver below the surface immediately
- will circle around, go away and then cautiously return
- gives time to decide whether to remain or return to the surface
- if returning to the surface, use a rhythmic beat with feet and do not make disturbance in the water as you move toward the boat
- if wearing scuba, remain submerged in water until reached boat
- if there is no time to leave, try not to panic
- best protection lies in ease of movement in diving
- swimming slowly and softly, avoiding abrupt change of position
- dangerous to dive at night
- dangerous to show fear of a shark, he knows this by instinct, and can profit from it
- wearing boldly striped or a patterned swimming suit may be hazardous
- there are no effective means of keeping sharks away from the area in which you are diving, either by chemical products, sound waves or fields of electricity
- always swim with a partner
- all things considered amongst causes of premature death, sharks must be ranked far below cars, motor cycles, alcoholism, excessive smoking, and narcotics.
- have a 1 in 5million chance of being attacked by a shark
- a better chance of being struck by lightening

Budker, Paul. The Life of Sharks. New York: Columbia University Press, 1971. 41-101

Cousteau, Jacques-Yves, and Philippe Cousteau. The Shark" Splendid Savage of the Sea.
Farden City, New York: Doubleday & Company, Inc.,1970. 229-240.

Faughnan, Victor R. The National Shark-O-Pedia. Honolulu, Hawaii: Uudersea
Resoueces, Ltd,. 1980. 1-9.

Gold, Joy P., and Victor G. Springer. Sharks in Question. Washington, D.C.:
Smithsonian Institution Press, 1989. 51-94,

Harrigan, Bill. "Shark Diving Bahamas Style." Bahamas Diver 1998/1999: 10-12.

Pope, Patricia E. A Dictionary of Sharks copyright 1973 Great Outdoors Publishing
Company St. Petersburg, Florida. 5-7, 78-86.

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It is 3:54:00 PM on Thursday, May 28, 2020. Last Update: Sunday, April 30, 2000