Sharks belong to a family of fish that have skeletons made of cartilage, a tissue more flexible and lighter than bone. They breathe through a series of five to seven gill slits located on either side of their bodies. All sharks have multiple rows of teeth, and while they lose teeth on a regular basis, new teeth continue to grow in and replace those they lose.

Shark ‘skin’ is made up of a series of scales that act as an outer skeleton for easy movement and for saving energy in the water. The upper side of a shark is generally dark to blend in with the water from above and their undersides are white or lighter colored to blend in with the lighter surface of the sea from below. This helps to camouflage them from predators and prey.

Most species of shark eat things like fish, crustaceans, mollusks, plankton, krill, marine mammals and other sharks. Sharks also have a very acute sense of smell that allows them to detect blood in the water from miles away.

It is difficult to estimate population numbers since there are many different species spanning a large geographic area. However, overall shark numbers are on the decline due to the many threats they face in the wild.

Sharks predate the dinosaurs by 200 million years. The largest known species of shark, C. megalodon, might have reached a maximum length of 67 feet.

Sharks have adapted to living in a wide range of aquatic habitats at various temperatures. While some species inhabit shallow, coastal regions, others live in deep waters, on the ocean floor and in the open ocean. Some species, like the bull shark, are even known to swim in salt, fresh and brackish waters.

Most sharks are especially active in the evening and night when they hunt. Some sharks migrate over great distances to feed and breed. This can take them over entire ocean basins. While some shark species are solitary, others display social behavior at various levels. Hammerhead sharks, for instance, school during mating season around seamounts and islands.

Some shark species, like the great white shark, attack and surprise their prey, usually seals and sea lions, from below. Species that dwell on the ocean floor have developed the ability to bottom-feed. Others attack schooling fish in a feeding frenzy, while large sharks like the whale and basking sharks filter feed by swimming through the ocean with their mouths open wide, filtering large quantities of plankton and krill.

Sharks mature slowly, and reach reproductive age anywhere from 12 to 15 years. This, combined with the fact that many species only give birth to one or two pups at a time, means that sharks have great difficulty recovering after their populations have declined.

Soon after birth, sharks pups swim away to fend for themselves. They are born with fully-fledged sets of teeth and are able to feed and live on their own.

The largest living ray and one of the largest of all elasmobranchs , the giant manta ray (Manta birostris) is a stunning and graceful member of the devil ray family (Mobulidae). This giant fish is notable for its sheer size, with anecdotal reports of individuals measuring up to 9.1 metres across.

The giant manta ray has a distinctive body shape, with triangular pectoral ‘wings’ and paddle-like lobes extending in front of the mouth. Known as ‘cephalic lobes’, these are forward extensions of the pectoral fins which form a funnel-like structure while feeding, helping to channel plankton-filled water into the mouth. The lobes are rolled into a spiral when the giant manta ray is swimming.

The broad, disc-like body of the giant manta ray is just over twice as wide as it is long, and there is a small dorsal fin on the back , with a rudimentary spine immediately behind it, on the upper side of the tail . The tail of the giant manta ray is slender and slightly flattened, and is shorter than the width of the disc-like body. The giant manta ray’s eyes are located on the sides of its head, and its gills are on the underside of the body. The cavernous mouth is positioned at the front of the head and has rows of tiny, peg-like teeth on the lower jaw.

The colouration of the giant manta ray can be quite variable. Most individuals belong to a ‘chevron morph’, which is predominantly black above and white below, with large white ‘shoulder’ patches on the back . These conspicuous white patches occur on either side of a dark midline, and are more or less triangular or chevron-shaped, with hook-like extensions to the sides. There may also be small patches of white on the tips of the pectoral fins. 

The underside of the giant manta ray is largely cream to white, with varying degrees of dark spots and patches, mainly on the belly. There is usually a prominent black, semi-circular mark behind the fifth gill slit on each side of the body, and the rear margins of the pectoral fins have dark shading. The giant manta ray also has dark colouration around and inside its mouth.

The giant manta ray also occurs in a striking ‘black morph’, which is completely black above and mostly black below, except for a variably sized white area around the gills and belly. Dark spots are often visible on this white patch. Nearly all-white individuals have also been documented. Each giant manta ray possesses a unique pattern of blotches, spots and scars that can be used to identify individuals.

Manta rays were previously considered to be a single species, but have recently been split into two separate species based on differences in size, appearance, habitat and behaviour. The giant manta ray grows larger than the reef manta ray (Manta alfredi), and also has a non-functional tail spine, which is absent in the reef manta ray. 

The white shoulder patches of the reef manta ray form a ‘Y’ shape and gradually fade into the black of the back, whereas those of the giant manta ray form a ‘T’ shape and are clearly distinct from the black back. Reef manta rays also differ in having a white to grey rather than dark mouth, and the dark spots on their underside are more extensive.

Studies have suggested that there may be a third species of manta ray, but more evidence is needed before the species are split further.

Atlantic manta, chevron manta, chevron manta ray, devil fish, devil ray, devilfish, devil-ray, giant devil ray, giant oceanic manta ray, manta, manta ray, oceanic manta, oceanic manta ray, Pacific manta ray, pelagic manta, pelagic manta ray.

Brachioptilon hamiltoni, Manta hamiltoni, Raja birostris.

Manta Diablo, Manta Gigante, Manta Voladora.

Disc width: up to 7 m

up to 2 tonnes 

An exceptionally graceful swimmer, the giant manta ray almost appears to fly through the water using its large pectoral fins. This species is capable of both rapid speed and deep dives, sometimes reaching depths of over 1,000 metres. Giant manta rays have also been observed jumping clear of the water and landing with a loud splash, possibly as a form of communication or even play.

Despite its enormous size, the giant manta ray feeds on tiny planktonic organisms by filtering large volumes of water through its mouth. Food is strained out of the water using plates of pinkish-brown, sponge-like tissue between the gills, known as ‘gill rakers’. When feeding, the giant manta ray unfurls the fleshy cephalic lobes on either side of its head and uses them to direct water into the mouth. It often swims in slow somersaults as it gathers food, or sometimes scoops plankton up along the sea bed.

The giant manta ray is thought to make seasonal migrations to take advantage of rich feeding areas. Although it is generally solitary, loose aggregations may form where there is abundant food or for mating. This species is often host to smaller fish called remoras, which attach to the manta ray’s body and consume particles of food that fall from its mouth. The giant manta ray regularly seeks out ‘cleaning stations’, where cleaner fishes such as wrasses (Labroides spp.) pick parasites off its body.

Courtship in the giant manta ray can last for days, with a number of males following a female around in a ‘mating train’, competing for the right to mate. Eventually, one of the males grasps the tip of the female’s pectoral fin in its teeth, and the pair mate belly-to-belly. As in other rays and sharks, fertilisation is internal, with the male transferring sperm to the female using a pair of ‘claspers’ on the inner part of the pelvic fins.

The developing eggs remain inside the female’s body for up to 12 months and then hatch internally, so that the female gives birth to live young. The female giant manta ray is believed to give birth to one or occasionally two young, probably in shallow water and at night. Births may take place only once every two to five years. The newborn giant manta ray measures an impressive 1.2 to 1.5 metres across, and may double in size during the first year of its life.

The giant manta ray is believed to mature at a disc width of about 4 to 4.5 metres in males and 5 to 5.5 metres in females. This species is thought to be long-lived, with an estimated lifespan of at least 40 years. The only known predators of the giant manta ray are large sharks, orcas (Orcinus orca) and false killer whales (Pseudorca crassidens).

The giant manta ray is found in tropical, sub-tropical and temperate waters in all the world’s major oceans, between about 31 degrees North and 36 degrees South. It has been recorded as far north as southern California and New Jersey in the United States, Mutsu Bay in Japan, the Sinai Peninsula in Egypt and the Azores Islands, and as far south as Peru, Uruguay, South Africa and New Zealand.

This species is believed to have a wider distribution than the closely related reef manta ray, and is more migratory in its behaviour.

A more oceanic species than the reef manta ray, the giant manta ray is thought to travel vast distances across the open ocean. It appears to be a seasonal visitor to coastal and offshore sites, and is commonly seen along productive coastlines with regular upwellings, as well as around oceanic islands, offshore pinnacles and seamounts.

The giant manta ray often visits shallow reefs to feed and to be cleaned by ‘cleaner fishes’.

Eels are snakelike creatures, with long bodies, found in freshwater as well as salt water. Unlike land snakes, eels usually lack scales on their body. 

However, a few species can be found with tiny scales along their bodies. More than 100 vertebrae are found in eel's spine. It makes the creature very flexible. True eels are an order in themselves (Anguilliformes), which consists of four suborders, 19 families, 110 genera and approximately 800 species. Genomic studies indicate that they represent a monophyletic group that originated among the deep-sea eels. 

Some eels dwell in water as deep as 4,000 meters. The most common type of eel is the Green Moray. Eels are mostly predators. Pollution, changes in the environment, over-fishing, drainage and hydro development are the main reasons for the reduction in eel population. Want to know more? Read through the following lines to know some more interesting and amazing information about Eels.

 

 

Kingdom: Animalia

Phylum: Chordata

Class: Actinopterygii

Super order: Elopomorpha

Order: Anguilliformes

Length: 5 feet to 13 feet

Weight: 95 gm to 215 gm

Lifespan: 85 years

Diet: Carnivorous

Habitat: Water

 

• Eels live near rocks and little caves. Most true eels prefer to dwell in shallow waters or hide at the bottom layer of the ocean, sometimes in holes. These holes are called eel pits.

• Eels begin their life as flat and transparent larvae, called leptocephali. This eel has sharp teeth and bites. Eel larvae drift in the surface waters of the sea, feeding on small particles called marine snow.