Ocean Predators Page #3

in the ocean.

There is limited understanding

of their reproduction.

Like most bonefish,

they spawn into the open water,

where the larvae develop into adults.

They are oviparous,

meaning they spread their egg cells

in the open sea.

Full moon seems to be

the preferred time to spawn.

They assemble in great swarms

at the edge of rock and coral reefs.

These little nippers roam in groups.

This is typical behaviour

for young barracuda

as they mainly hunt small fish.

The adult animals would

never be satisfied with small nibbles.

Instead, they prey on mackerel

on the high seas.

These speedsters can even

keep up with young tuna fish.

The barracuda is

not only native to the Pacific,

they can be found in

tropical and subtropical oceans

and have even been known

to visit the Mediterranean area.

Barracuda are very fast and deadly predators

who spread over large parts of the world.

More than any other shark,

this species have to rely on

speed and surprise to catch their prey.

Even if we sometimes

wish this killer

is not able to catch

their victim,

the barracuda contributes an important part

to the balance of the sea world.

So we are lucky to have

such a skilled hunter in our oceans.

These eagle rays calmly

orbit over the corals in search of food.

But this reef belongs to the hammerheads.

The hammerhead sharks,

with their hammer-shaped head,

are the most curious looking sharks.

The great hammerhead

can grow to truly giant proportions.

The head is widened by its cephalofoil.

The cephalofoil looks like a bent rectangle,

which is the typical form of

a hammerhead shark head.

The hammerhead has

settled all around the world,

where we find tropical and warm waters,

but he always

remains very close to the coast.

Up until today, we know about

nine different types of hammerheads.

Some hammerheads grow

to a length of around 13 feet.

But even more impressive than their size

is their ability to sense electricity.

This is equivalent to a human being

sensing the electrical current

given off by a 12 volt battery

through two floors.

Hammerhead sharks are present

in almost every ocean on earth,

but they especially love the warmer regions.

They feed on fish, crustaceans,

squid and stingrays.

Hammerheads are one of the rare species

which can reproduce without a partner.

Genetically, the offspring is a clone,

because the genotype

is identical to their mother's genotype.

This kind of reproduction

only usually occurs in smaller species

such as insects, snails and amphibians.

So it is particularly astonishing

to observe it taking place

in a species as large as the hammerhead.

But unlike these small creatures,

the hammerhead does not lay eggs.

They instead give birth to living offspring.

This, and the fact that sharks are

very difficult to keep in captivity,

resulted in the first observations of the

parthenogenesis reproductive technique

happening only about 10 years ago.

But scientists are certain

that this type of reproduction

only happens under unique circumstances.

The young scalloped hammerhead sharks

are found in groups

that can grow

to several hundred in strength.

They swim along the coast in swarms,

using their powerful sonar to, literally,

scan their surroundings for prey.

This sonar is so effective

that the hammerhead shark is far more likely

to find prey in their hideouts

than any other kind of shark.

The reason being its head

which has many advantages.

Ampullae of Lorenzini are organs

that can read electromagnetic fields

and they are arranged in three

different centres on

the shark's head.

This helps the hammerhead

locate the heartbeat of its prey

much easier and faster than its rivals.

Its eyes are located

at the two ends of the head.

As a consequence, the hammerhead has

an advantage over other species

as he has a wider field of vision

for a better perception of his environment.

The cephalofoil of the hammerhead shark

doesn't only contain

the Lorenzini ampullae.

It is said that the wider head

improves its ability to manoeuvre

and also increases his perceptual field.

The eyes and the large nasal passages

are located on the outside of the head,

so that their sensory organs are

able to detect prey in a wider field.

In addition to these great senses,

the hammerheads are also

equipped with a very large dorsal fin.

An advantage for quick navigation.

But, too often, their fins

fight the final battle.

They are high on top of the list

for shark fin traders.

Experts estimate that the species

of scalloped hammerheads

and smooth hammerheads,

are dying at a rate of one

to almost three million animals per year,

due to the fin industry.

The hammerhead shark young are born

in the shallows of coasts and in bays.

They regularly fall victim to fishing nets,

caught in droves

when in close proximity to the coast.

In open water,

long lines, bottom nets, and trawls

tend to interfere with the hammerheads.

Hammerhead sharks are

valuable fish in longline fishing.

They are caught as,

so-called, "unwanted" bycatch.

But are often, illegally,

a very welcome catch.

And increasingly substituting

overfished species such as tunas.

Conservationists have been fighting

for a regulation of shark fisheries,

and a ban on shark finning.

Success is not yet in sight.

Humans are not the only ones

who consider the hammerhead sharks

a part of their diet.

Consequently, the hammerhead

must always be on guard

when larger creatures are around.

This giant, proud and spectacular creature

is moving towards the sharks.

Growing up to 50 feet in length,

the whale shark

can be particularly intimidating.

The hammerhead indeed appears scared,

and so makes quick its escape.

But this panic is not necessary.

This giant is a rather harmless fellow.

Just like basking sharks

and megamouth sharks,

the whale shark filters plankton

and similar organic material from the water.

Even though small mackerel or young tuna

are sometimes found

in the stomachs of whale sharks,

they are, in fact,

completely harmless to humans,

despite their colossal stature

and predatory appearance.

Although the whale shark

is the largest of all living fish,

it is also the most peaceful.

It glides through our oceans

with his 20 tons,

as peaceful as clouds through the sky.

Any person who has been

lucky enough to encounter a whale shark

will describe

it as a breathtaking experience.

Most people are

amazed by their sheer size alone,

but they also boast

an amazing pattern on their skin

and move elegantly and gracefully

through the water.

Their large fins

seem to swing in slow motion,

and their whole presence

is an amazing spectacle to behold.

However, the whale shark

with its great size and presence

is not the predator it might appear.

It is, in fact, just another creature

on a long list of endangered species,

and is, so, not ranked in our list

for the world's most dangerous predators.

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