Sharks And their relatives…

Great White VR video

Elasmobranch Members of the elasmobranchii subclass have no swim bladders, five to seven pairs of gill clefts, rigid dorsal fins, and small placoid scales. Includes 250 species of sharks and 500 described species in thirteen families of rays

Sharks are amazing fish that have been around since long before the dinosaurs existed. They live in waters all over the world, in every ocean, and even in some rivers and lakes. Unlike bony fish, sharks have no bones; their skeleton is made of cartilage, which is a tough, fibrous substance, not nearly as hard as bone. Sharks also have no swim bladder (like bony fish do).

Do sharks lay eggs? Oviparous sharks lay eggs with thick cases that are resistant to predators, which they attach to rocks or seaweed. The eggs hatch days, or weeks, later, leaving the young to fend for themselves. Most egg cases are broadly rectangular and some, such as the dogfish's ‘mermaid’s purse’, are commonly washed up on seashores. Viviparous sharks give birth to live young, which are nourished in the female shark’s uterus via a placenta, or a secretion known as uterine milk. Viviparity ensures that the young are very well nourished during development and thus fit to survive the rigours of the sea immediately after birth. Ovoviviparous sharks also support the embryos internally and give birth to live young, but they do not provide any direct nourishment to their offspring. Instead, the developing sharks rely on the egg’s yolk sac for sustenance. Some species of shark, such as the mackerel sharks, practice oophagy, whereby the mother produces a stream of small, unfertilised eggs that are eaten by the developing embryos.

The egg sac of a Dogfish shark, commonly known as a "Mermaid's Purse."

General Shark

Those famous teeth….. Sharks may have up to 3,000 teeth at one time. Most sharks do not chew their food, but gulp it down whole it in large pieces. The teeth are arranged in rows; when one tooth is damaged or lost, it is replaced by another. Most sharks have about 5 rows of teeth at any time. The front set is the largest and does most of the work

What about the blood? A shark's primary sense is a keen sense of smell. It can detect one drop of blood in a million drops of water (25 gallons or 100 liters) Sharks can detect a concentration as low as one part per billion of some chemicals, such as certain amino acids. Sharks can smell blood 0.25 mile (0.4 km) away Its paired nostrils are on the underside of its snout. Water continually flows through the nostrils, giving the shark olfactory information. Unlike humans, shark nostrils have nothing to do with breathing - they are not even connected to the mouth.

Do Sharks Sleep? Fish don't sleep in the same way that we do, but they have active and inactive periods. Some sharks (like the nurse shark) have been observed resting motionless on the sea floor. Others have to keep moving in order to breathe.

Fun Facts: More people are killed by bee stings than by shark attacks. More than 90% of people who are attacked by sharks survive the attack. Sharks' bodies are heavier than the sea, so if they stop moving they sink. If they want to stay afloat, they must keep moving!

The bull shark is the only shark that can live in both fresh and salt water. A bull shark may have been responsible for a shark attack that happened in a creek in New Jersey back in 1916

No Cancer? It was thought that sharks never get cancer! It was the craze to take shark cartilage (powdered) because it had cancer fighting properties. In 2000, researchers at John’s Hopkins discovered several types of tumors and cancers in various sharks…. What would be the effect on sharks if their cartilage actually could prevent cancer?

Shark skin Shark skin is covered with tiny tooth-like structures called denticles that protect them from abrasion, parasites, and helps them to swim efficiently by reducing drag

Unfortunately…

Shark relatives: Skates, Rays and Chimaeras Chondrichthyes!!!

Skate or Ray? Skates and rays can be difficult to differentiate. Both are flat and (with a few notable exceptions, such as the eagle and manta rays) bottom-dwelling elasmobranchs sharing a similar diamond or rhomboid shape. Chimaeras? On the whole, chimaeras are rather peculiar-looking, deep-sea fishes. They have a disproportionately huge head pocked with large, well-developed eyes. They have an odd, rabbit-like mouth filled with plate-like grinding teeth. The tail is tiny and often streamer-like, so for propulsion chimaeras rely instead on flapping their large, wing-like pectoral fins. Chimaeras in 'flight' resemble a kind of weird cross between a fish and an angel.

Rays The biggest ray is the Manta ray which is over 22 feet (6.7 m) wide and weighs many tons (thousands of pounds).

Remoras (another type of fish) are frequently seen with mantas, staying near the manta's mouth (even going inside the gill cavities). The remoras probably feed on parasites on the manta's body and eat bits of the manta's food.

The smallest ray is the Short-nose electric ray, which is the size of a pancake; it is only 4 inches (10 cm) across and weighs about 1 pound (0.5 kg).

Electric rays have specialized organs that can deliver a specific electric charge if provoked. This can stun an attacker, or prey! PACIFIC ELECTRIC RAY

Skates

Chimaeras

ampullae of lorenzini? The ampullae of lorenzini are small vesicles and pores that are part of the skin’s sensory network system. These pores detect weak magnetic fields produced by other fish and allow it to locate prey that are buried in the sand.

Sharks common to Nova Scotia These are the shark more commonly found in the Bay of Fundy

Have been seen and tagged….many recently

Rare Species These are the sharks less common to the Bay of Fundy but are familiar to the Atlantic Region.

The biggest shark is the whale shark (Rhincodon or Rhiniodon typus), which can be up to 50 feet (15 m) long. It is a filter feeder and sieves enormous amounts of plankton to eat through its gills as it swims

And still more:

Shark Facts Great White (Carcharodon carcharias) grows to be up to 21 feet (6.4 m) long. Great whites up to 37 feet (11.3 m) long have been reported, but not verified.

MOST COMMON SHARK The piked dogfish shark (Squalus acanthias) is very abundant, especially in the North Atlantic Ocean. It is a small shark, about 63 inches (1.6 m) long.

DEEPEST DIVER The Portuguese shark dives down over 9,000 feet (2750 m). This is over 1.5 miles

Biggest shark ever! The largest shark known was the Megalodon (Carcharodon or Carcharocles megalodon); it is now extinct. It was an ancient, meat-eating shark that lived between 25 million and 1.6 million years ago. It was up to 40 feet (12 m) long and its teeth were each the size of a person's hand!

Smallest Shark The smallest sharks are: Dwarf Lanternfish (Etmopterus perryi), which is about 7 1/2 to 8 inches (19 - 20 cm) long for fully-grown females and 6 to 7 inches (16 - 17.5 cm) long for adult males

Most Dangerous..? (debateable ) The oceanic white-tipped sharks are the most fearless predators. Jacques-Yves Cousteau says that it is: "the only species of shark that is never frightened by the approach of a diver, and they are the most dangerous of all sharks."

Fastest The fastest swimming sharks are the mako sharks and blue sharks, which can even leap out of the water. They are also probably the fastest fish. Estimates of their speed varies; some say that they can swim at about 60 miles per hour (97 kph), while more conservative estimates are about 22 mph

Longest Tail thresher sharks -the upper lobe of their tails are about the same length as their bodies.

STRONGEST SHARK BITE The strongest shark bite belongs to the dusky shark (Carcharhinus obscurus); its jaws have been measured to exert 132 pounds (60 kg) of force per tooth

Largest Litter One Blue shark was found with 135 pups in her uterus.

Other types: necklace carpet shark

goblin shark

great hammerhead shark

smooth hammerhead shark

megamouth shark

sand tiger or gray nurse shark,

broadnose sevengill shark or cow shark

ornate wobbegong

SHARKWATER Question set to go with