Beluga Whale

Beluga or "white whales" are not born white. They are grey at birth and get lighter and lighter until at about age six they are completely white. Belugas are one of the three whales that spend all their lives in arctic waters. The other two are the bowhead and the narwhal. Beluga are special among all whales because they can turn their heads. Maybe this is so that they can communicate with each other better! Beluga are very social and make a wide variety of sounds. A group of beluga can be loud! They have been nick-named "sea canaries." Beluga use sound to help them find their prey. They send out a sound which bounces off things in the water and allows them to hear how far away something is. This is called "echolocation." Beluga will work together using this and other techniques to herd fish into shallow water. It has also been reported by native people that beluga whales help each other give birth! They use many subtle forms of communication including a wide variety of facial expressions. Unlike some other whales, beluga have good vision.What they don't have is a dorsal fin, earning them the name "delphinapterus" or dolphin-without-a-wing. 19th Century Naturalist Edward Nelson Recounts: "In January,  1879, while sledging near the mouth of the Kuskoquim River, a considerable number of White Whales were seen one evening among the broken ice near shore.  They were in an irregular school containing twenty or more individuals.  They are seen sometimes in winter off the Yukon mouth when the ice is driven off shore or broken up. At Point Hope on July 20, 1881, the females were seen swimming up and down the shore singly, each with two or three males keeping close alongside.  Each female was accompanied by a young of the year, which kept close above its mothers back or just behind her. At Saint Michaels the first ones seen in spring usually arrive between the 5th and l0th of June soon after the ice moves offshore or leaves the inner bays.  This is the spawning time for the herring which swarm along the shore and the White Whales follow them into all the bays and inlets.  On calm June mornings great schools of these whales, numbering from twenty to over a hundred animals, are frequently seen in the bay at Saint Michaels, and their glistening milk-white color shows handsomely against the dark green water. About the middle of June the first young are seen.  For the first few weeks after their birth they are very small, and have a great bulging forehead, which extends beyond a vertical line from the end of the jaws.  Their color is a dark livid bluish or dull bluish green, so dark that they look almost black when seen at a distance in the water.  They keep close to their mothers, and the latter swim very carefully, the young usually resting on their backs just beside the thin upward extension of the skin, which appears like a false fin.  During the remainder of the season they are generally distributed along the coast.  The closing of the bays and streams by ice the last of October drives them off shore and south each autumn."

Beluga Whale

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Megalodon

One of the most deadly and dangerous sharks is the Great White, which can grow to lengths of 20 feet. less than two million years go, however, we would've had the Megalodon to deal with. It is perhaps the largest predatory fish ever to exist, sporting lengths of over 50 feet, and a jaw 7 feet wide. Their individual teeth could grow to 7 inches long, and during theRenaissance, fossilized teeth were thought to be the teeth of mythical dragons! It wasn't until the late 17th century that scientists realized they were looking at a really, really big shark. (Teeth are really the only remnant that we have of these beast, as cartilage fossilizes very poorly)

Really, really big shark.

Image from Thinkquest

So what did the Megalodon eat? In short, probably everything. It is estimated they they consumed up to 2,500lbs of food each and every day, which really doesn't seem like all that much when you consider that they have to power a muscular body that weighs over 50tons. They most likely consumed whales of the time, as well as fish, and other sea mammals. Megalodons lived in coastal areas around the world. Basically nothing fed on them.

Image from Karen Carr

No one is 100% sure about why the Megalodon went extinct. They dominated the seas for nearly 20 million years, and then all died out about 1.6 million years ago. Habitat changes and loss of prey may have been the culprits. Some cryptozoologistsbelieve that the Megalodon is still out there, due to unconfirmed sightings and the fact that it's extinction is relatively recent. However, due to the size and thecoastal habitats of the Megalodons, their continued existence is pretty unlikely.

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The whale shark

The whale shark is thought to have developed around 60 million years ago making the whale shark one of the oldest species on Earth today. The whale shark is the largest species of fish with some adult whale sharks growing to nearly 50ft long. Unlike many other species of shark, the whale shark is known to feed on large shoals of tiny fish rather than hunting bigger fish and sea mammals. This makes the whale shark a filter feeder similar to whales and smaller sea animals.

The whale shark is the perfect example of a so-called friendly shark and to date have posed no significant threat to humans (mainly divers). The whale shark inhabits the warm, tropical waters around the equator and despite often being found close to coastlines, the whale shark is also known to dive to depths of up to 700 meters (that over 2,000ft deep). In this part of the ocean, food is more scarce and the whale shark will therefore only venture to such depths if hunting in the shallower waters is not possible. 

 

The whale shark is most commonly spotted around the Gulf of Mexico and the Indonesian Islands where the whale sharks have been known to be almost playful towards humans. Whale sharks tend to live for around 60 to 80 years but have been known be more than 100 years old. 

Female whale sharks incubate their eggs inside them rather than outside. This means that whale sharks effectively give birth to live young. Inside the female whale shark are hundreds of eggs but only a few actually turn into baby whale sharks. The remaining eggs are thought to be there so that when the whale shark pups hatch, they have something to eat. The female whale shark gives birth to an average litter of 12 whale shark pups that are around 60 cm long.

 

Whale sharks grow quickly during their first few years and soon the whale shark pups areextremely big and therefore less likely to be hunted by marine predators such as other shark species and killer whales. 

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Atlantic Sharpnose

The Atlantic sharpnose shark is a requiem shark of the family Carcharhinidae. These sharks prefer subtropical waters nearcontinental shelf outside of the intertidal zone to deeper waters. They are often found nearthe surf zone of sandy beaches and closed bays, sounds, harbors, estuaries and river mouths. This shark is able to tolerate low salinity, but they do not venture into freshwaterbull sharks. Atlantic sharpnose sharks are found in the western Atlantic from NewBrunswick, Canada south to the Gulf of Mexico and the Southwest Atlantic along the coastof Brazil in waters ranging from 10 to 280 m.

 

Atlantic sharpnose sharks are small, gray, streamlined shark, with characteristic long,pointed snout. The males reach at least 1 m long, females may be slightly higher to 1.1 m.Their average weight is 7.25 kg. The edge of the anal fins are straight or slightly concave.Their second dorsal fin located behind their anal fins. Atlantic Sharp Nose sharks are known to be at least 10 years of age to reach.

 

Sexual maturity is reached when an Atlantic sharpnose shark is about 83 cm. The young are fed into the female viviparous development. Litters of 4-7 pups are born in June in shallow water or estuaries. Newborns are 22-35 cm in length. Atlantic sharpnose sharksfeed on small bony fishes, shrimps, crabs, worms and mollusks. This shark, like most, is harmless to humans. The Atlantic sharpnose shark is a common nuisance to fishermen 

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Lemon Shark

The Lemon shark is a shark in the familyCarcharhinidae. It is known as the Lemon shark, because at some depth, light interaction with the local sea shark can give a tanned look pitted and yellow, like the size of a lemon.Lemon sharks are usually found in subtropical shallow waters near coral reefs, mangroves, closed bays, and the sounds and estuaries, while Lemon sharks do not seem to travel far into fresh water. They can be found in open water during migration, but in general they tend to stay along the continental and insular shelves. This species is known to groups based on size and sex and shape are seen in groups near fishing docks and piers at night to return to deeper water during the day.

Lemon sharks are named for their pale yellow to brown color on their dorsal (upper) side and a lighter yellow on their belly (lower) sides. The growth rate of the lemon shark is 0.54 cm per year. This species has two dorsal fins of similar size, the first is far back on the body behind the pectoral fins, second dorsal fin is located slightly forward of the origin of the anal fin. No interdorsal ridge. The ventral fin is slightly concave rear margins and the outer edge of the pectoral fin is slightly convex. Both the pelvic and pectoral fins are slightly curved. This shark has a blunt, short snout.

The Lemon shark is viviparous, meaning that women form a placenta-like connection to each of the developing fetus and eventually give birth to live free swimming puppies.Females and males reach sexual maturity at 6-7 years of age or at 2.4 m and 2.24 m respectively. Mating occurs in spring in shallow water, followed by a 10-12 month gestation period. Females return to shallow soils nurse from April to September to give birth to 4-17 pups measure between 60-65 cm external. Pups remain in the nursing grounds for several years, expanding their range as they grow.

Lemon sharks feed on bony fish, including: catfish, mullet, jacks, pill, porcupine fish, and Cowfish and guitar fish, stingrays, eagle rays, crabs and lobsters. Occasional lemon sharks also eat small sharks and seabirds. All the Sharks have electroreceptors concentrated in their heads, called the ampules of Lorenzini. These receptors detect electrical pulses emitted by potential prey. Lemon sharks are bottom dwellers. They have poor eyesight and can not see to find their food, but are equipped with highly sensitive and accurate magnetic sensors in the nose.

Lemon sharks are both commercial and recreational hunting. U.S. longline goal lemon sharks and they are also caught as bycatch in the gillnet and pelagic. Their fins are sold for shark fin soup, and their skin is sold for leather. Lemon sharks are also sold for their meat.Population in the western North Atlantic and eastern Pacific are due to decreasing over-fishing. Lemon sharks are potentially dangerous to humans, but the International Shark Attack File only reported 10 unprovoked bites lemon sharks, all of which happened in Florida and the Caribbean.

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Great White Shark

GSW has a "torpedo shaped" body with a pointed snout. The belly of the shark is white (hence its name) but the top of the shark is actually grey making it hard to spot from above. "Average" size is around 3 1/2 to 5 meters long and weighing about 1,200kg with the females being larger than the males. They can have up to 3,000 teeth located in rows. Each tooth is saw toothed and triangular shaped. As a tooth is broken or lost it is replaced by a tooth from the next row, so the GWS always keeps a full mouth of teeth. The Great White Shark or sometimes called the "Great White" scientific name is Carcharodon carcharias. 

 

There are over 600 species of Sharks and rays with the GWS (Great White Shark) belonging to a group of fast-swimming sharks called mackerel sharks GWS are usually solitary animals but have been seen in pairs and even occasionally in groups up to 7 or 8. Location of Great White Sharks The GWS is found in temperate (mild) waters fairly close to the shoreline They are found in most parts of the world including North & South America, Africa, Japan, China, Russia, New Zealand, and of course Australia

DIFFERENCE TO FISH

GWS are fish, but unlike most fish do not have bones but rather a "cartilaginous skeleton" 2 other differences are their scales which are not smooth and oily like most fish but very rough like glasspaper, and their gills (gill slits) which are not covered like most fish but are open. GWS are predatory (eats other animals fish etc) Their food includes other sharks, fish, sea lions, seals and other marine mammals, turtles, small whales. GWS are also scavengers eating animals already dead (Carrion) Despite having teeth GWS do not chew their food but swallow whole pieces ripped off their victim by their teeth

HUNTING

GWS swiftly attacks its prey from below taking a bite and letting the victim bleed to death. To locate its prey the GWS uses its very excellent sense of smell (especially of blood) and an ability to sense "electrical charges" given off by muscle movements. They sense these by their ampullae of Lorenzi, located in the pores around their snout. These are small tubes that pick up the information, and then send it to the brain.

SWIMMING
These sharks use their tails to push them through the water and their fins to keep themselves balanced. They must constantly swim or else they will sink. The reason they would sink is, unlike bony fish (osteichthes), they do not have a swim bladder which holds air. The swim bladder in the bony fish can be controlled by valves. When the want to get more air in they open a certain valve, so they can rise. If they want to go lower in the water, they open another valve to let the air out. The air lets them float. The sharks do not have these, which is why they must keep swimming or they sink.  GWS give birth to live young which are called pups. The pups fully develop inside their mother and once born they are immediately independent from their mother.

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Grey Reef Shark

The Grey reef sharks are one of the smaller species of shark with adults reaching a maximum length of around 2m long. The grey reef shark is one of the most common species of shark found in the warm waters of the Indian and Pacific Oceans. Grey reef sharks are generally found in the coastal regions and along continental shelves from the Middle East to the islands in the deep Pacific.

The grey reef shark tends to move about slowly gliding silently through the water at speeds that often do not exceed a few miles an hour and the grey reef sharks are commonly known to lay on the ocean floor for long periods of time. However, when the grey reef shark detects food in the water, the grey reef shark is known to suddenly become very active and quick, with the grey reef shark often becoming fairly aggressive if there is food about.

Grey reef sharks feed on reef fish, squid and shrimp. The grey reef shark is not thought to pose a great threat to humans and the grey reef shark has been noted to be inquisitive towards divers. Other species of reef shark include the white tipped reef shark, the black tipped reef shark and the Caribbean reef shark, all of which belong to the same family so have similar characteristics to the grey reef shark.

The grey reef shark has a very distinctive shark-like appearance which includes the long slender body of the grey reef shark, large fins and a rounded snout. The grey reef shark tends to gather together in schools with other grey reef sharks during the day, but the grey reef shark is generally more active at night. The grey reef shark has very few natural predators in its coastal, underwater habitat as many larger water-bound carnivores tend to lurk in the deeper waters. 

When the grey reef shark feels under threat, particularly from larger species of shark or from humans diving, the grey reef shark tends to react in a very distinctive way with the grey reef shark arching its body up and moving its head slowly from side to side whilst the grey reef shark is swimming along. The grey reef shark is thought to do this to intimidate unwanted company rather than in preparation to attack it.

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