Shark Cart
Sharks, Rays & Skates
Sharks & Rays are a type of fish that do not have bones but instead have tissue that is made of cartilage (like our nose & ears!). This makeup allows them to move quickly through the water without using too much energy. The fins of sharks are used for stabilizing, steering, lift, and propulsion, all for different reasons. Sharks are considered keystone predator species as they act as population control and are crucial to the health of the ecosystems, they are a part of. Despite the fact they are known as one of the most important species in our oceans, approximately 75% of the species of sharks are considered endangered or threatened.
We have three ecosystems represented here at Loggerhead Marinelife Center, the Red Mangroves, Gulf Stream, and Coral Reef exhibits are geared towards educating guests about their importance here in Florida. Some of the species you might see in these places are as follows: Mangrove - Bull Shark, Coral Reef - Nurse Shark, Gulf Stream - Great White Shark, Tiger, Mako Shark
Our Shark & Ray cart covers a variety of different biofacts that are related to the shark and ray species you might find locally!
FINS: Have any of you ever SCUBA dived? How is swimming as a diver different from walking on land? In three-dimensional fluid environments like water/air an object must correct for 3 forces that oppose the direction of motion:
Roll - “spin” clockwise or counterclockwise
Yaw - nose “turns” right or left of the direction of motion
Pitch - nose “nods” up or down
The stiff fins of sharks are placed to control these 3 oppositional forces:
Dorsal / Anal: keels to prevent ROLL.
2 Pectorals: rudders to control YAW (steer).
2 Pelvic: control pitch to keep the fish horizontal (prevent ascent/descend)
1 Caudal / Tail: propels the fish (generates thrust)
Skeleton: A shark’s skeleton is mostly cartilage (collagen & protein), although spine, teeth and sometimes jaws may have some calcification for strength/stiffness. • Cartilage is half as dense as bone & therefore lighter. This is important because sharks lack a swim bladder & only have a large oily liver to help with buoyancy.
The spine of a shark extends into the tail for attachment of muscles.
Sharks lack ribs to protect internal organs. Held together by tough skin & muscle.
Scales & Dermal Denticles: Fishes have overlapping plate-shaped (cycloid) scales covered with protective slime. Shark scales have tiny ridges that all point towards the tail. These dermal denticles feel smooth/hydrodynamic when you rub from head to tail, but when rubbed backward (tail to head) the skin feels like rough sandpaper.
Dried Shark Skin (shagreen): has been used on samurai sword hilts for extra grip.
“Skin Teeth” create tiny vortices to limit drag & turbulence for more efficient swimming, similar to how the dimples on a golf ball work.
Speedo designers created FastSkin fabric purported to bio-mimic shark skin to improve human swim times. “LZR suits” debuted 2008 Beijing Olympics where 23 swim records were broken (users incl US athlete Michael Phelps).
At the 2009 World Championships, German swimmer Paul Biedermann beat Phelps who wasn’t wearing the Gen2 “X-Glide” full-body suit, that was banned from use in the 2010 Vancouver Olympics.
Interestingly, Harvard researchers testing polyethylene fabric found the super tight swimsuits squeezed athletes to be more streamlined & improved venous circulation to tired muscles.
Swimsuits such as the Speedo Fastskin II have no effect when it comes to reducing drag as swimmers move through the water. [REF: Katherine Knight. 2012. Shark Skin produces propulsion. JEB 215 (5)
Ampullae of Lorenzini:
Electroreceptors that act as sense organs to detect electric fields. They form mucus-filled pores in the skin of cartilaginous fish, sharks and rays, and help them detect movements in the water or sand.
TEETH: Sharks have an average of 3-15 rows of replaceable teeth. Usually, only the first 2-3 rows are functional. “Reserve teeth” lie flat & move forward to point upright as they reach the outer edge of the mouth. Sharks are always growing new teeth & due to loose placement in gums (no roots) may lose 30 teeth/ month. The rate of tooth replacement varies by species & ranges from 9 - 36 days
FOSSILIZED TEETH: Sharks can shed thousands of teeth in their lifetime, but for them to be considered fossilized they are estimated to be at minimum 10,000 years old. Here in Florida, many of the fossilized shark teeth that are found are estimated to be between 10-20 million years old. The process of fossilization is fascinating, as it requires that the tooth sinks to the ocean floor, rapidly become covered in sediment, and then the sediments absorb surrounding minerals that contribute to the black-gray-tan coloring that fossilized teeth get.
JAWLINE: Sharks have unique jawlines that help them break down the many animals they predate upon.
Nictitating Membrane: A shark’s eye is similar to humans in that it has a pupil that reacts to light and movement, and anatomically has a cornea, iris, retina, and lens. However, some sharks have a third eyelid known as the nictitating membrane, which acts as a protective layer, and helps keep their eyes moist. This eyelid response is usually seen when sharks are feeding or fighting and will slide down over their eyeball for protection.
Roughtail Stingray or Thorny Stingray (Bathytoshia centroura)
Size: Largest whip-tail stingray, max 7.25ft, >660lb.
Description: The thorny tail can be >2.5X body length. Has a massive venomous serrated tail barb.
Avoid handling or exercise extreme caution Distribution: Cape Cod MA to Gulf of Mexico & Bahamas
Bull Shark (Carcharhinus leucas)
Size: Max 13ft/700lb. Sm eyes, stout bodies
Description: Series of 5 attacks over 12d Matawa NJ 1916, 4 fatal, said to be Peter Benchley’s inspiration for 1974 book “Jaws” that Steven Spielberg made into 1975 movie
Diet: Mostly bony fishes & sm sharks. Can spend long periods of time in FW. Its size, abundance & proximity people = 100 unprovoked attacks humans globally, 27 fatal, probably many unreported.
Tiger shark (Galeocerdo cuvier)
Size: Max18ft/2000lb. Avg <14ft/< 1400 lbs.
Description: Large eyes, blunt snout. Juveniles have numerous dark spots that form into stripes. Mature adult markings faded. Frequents murky waters in coastal areas & estuaries. Usually solitary hunter. Teeth: distinctive teeth + saw-like action as shaking the head back & forth tears chunks from much larger prey
Diet: Eats/scavenges anything including sea birds, sea turtles, & even garbage.
Sand Tiger Shark or Ragged/Snaggle tooth Shark (Carcarias taurus)
Size: Max18ft/2000lb. Avg <14ft/< 1400 lbs.
Description: Large eyes, blunt snout. Juveniles have numerous dark spots that form into stripes. Mature adult markings faded. Frequents murky waters in coastal areas & estuaries. Usually solitary hunter. Teeth: distinctive teeth + saw-like action as shaking the head back & forth tears chunks from much larger prey
Diet: Eats/scavenges anything including sea birds, sea turtles, & even garbage.
Nuse Shark (Ginglymostoma cirratum)
Size: They can grow up to 14ft in length
Description: Nurse sharks are slow-moving, bottom-dwelling, and mostly harmless to humans. They have strong jaws with thousands of tiny, serrated teeth and use barbels (they look like whiskers), which are fleshy organs that have taste buds, to drag along the bottom of the sea floor to find prey. Nurse sharks have also been observed in “cuddle” behaviors or using their pectoral fins to ‘walk’ along the bottom, instead of swimming!
Diet: Generally, consists of snails, crabs, clams, small fish and other small invertebrates.