Goblin Shark Footage

Goblin Shark Video

Introduction to Hammerhead Shark

Even if you struggle to keep various species of sharks clear in your mind from the rest, this is one that you will easily remember. They have the unique shaped head that has made them such a fascinating to experts as well as to the general public. There is no other species of shark out there compared to the look of the Hammerhead Shark.

Hammerhead Shark Description

As mentioned, this species of shark has a head that is wide like the head of a hammer and then a long handle as it goes back to the rest of the body. This shape is actually appropriately called cephalofoil. This shape allows them to have excellent sensory receptors, to easily manipulate their prey, and for them to move around in the water with ease.

There are several subspecies of them, and they can dramatically vary in size. Some of them are only 3 feet long and others can grow to a size of up to 20 feet long. They can also vary a great deal in weight from 500 pounds up to 1,000 pounds. Both location and their food sources also influence the overall size of Hammerhead Sharks.

They feature a light gray color but if you pay close attention to them you will also see a green-colored tint as well. They have a white belly so that they can easily sneak up on their prey in the water. It is believed that they have better vision than other species of sharks due to the shape of the head and location of their eyes. They have a 360-degree vision so that they can see above and below them in the water at the same time.

They also rely on their electro receptor sensors so that they can feel vibrations and movements in the water. This makes it very simple for them to find prey even if it is barely moving in the water. Their mouths seem to be very small in proportion to their heads.

Hammerhead Shark Distribution

Hammerhead Sharks are found in many bodies of water around the world that are warm. They tend to live the most often through the continental shelves and the coastlines. Large numbers of them have been identified around Cocos Island close to Costa Rica and Molokai Island close to Hawaii. There are also many of them around both Eastern and Southern Africa.

During the summer months, the Hammerhead Shark migrates in very large numbers. They do so in order to find cooler waters where they will stay for the hotter period of the year. This is also when a great deal of the mating will occur and the migration allows them to find the greatest genetic pool to select from.

Hammerhead Shark Behavior

While most species of sharks are loners, the Hammerhead Sharks swim in schools during the daylight hours. These schools can have up to 100 members in them. At night time though they go to find food and they do that on their own. It is believed they spend time together during the day for protection but also that they enjoy socializing to some degree as well.

They aren’t known to attack humans, but they will do so if they are provoked and feel that they must do so in order for their own protection. This is especially true of females that are about to give birth. They aren’t territorial but they are instinctively going to do what they can to protect their needs.

Hammerhead Shark Feeding

Due to the ability to pick up movements in the water, they have very little trouble finding their prey. This combined with how well they blend into their surroundings and their ability to see and they are able to get food without wasting energy. They do eat large amounts of food every day and will consume all that they can find readily available. They are nocturnal which means they do their feeding at night.

Their diet consists of quite a variety of products. They include octopus, fish, squid, stingrays, crustaceans, and small sharks including baby Hammerhead Sharks. They tend to look for their food at the bottom of the water and they are very good predators. They use their head to pin down some prey such as stingrays. They consume their prey while it is in shock and unable to move. In some instances when food is very hard to find, the females have been known to consume their own offspring.

Many experts agree that this species so shark has the greatest advantage over other species due to the shape of the head and their eyesight. This could be a prime reason why they aren’t as at risk of dropping numbers as many other species.

Hammerhead Shark Reproduction

The rituals for mating may seem harsh from our point of view as the males fiercely bite the females. However, the females have very thick skin so they aren’t in pain from those bites. Still, many of the older females do have plenty of bite marks on their bodies from this process. Mating occurs annually for the Hammerhead Sharks and that helps them with increasing their numbers. Many other species of sharks reproduce at a much slower rate.

The females are in control over mating, and will often eventually give in to the advances of the male. However, she can decide to make him go away and wait for another male to mate with. These rituals can take hours though for the female to decide one way or the other.

The females give birth to live young, but they are left to take care of their own needs as soon as they are born. The litter can have from 12 to 15 pups in it but there is one species that can have up to 40 at a time. The young depend on the safety in numbers and swim as a group towards warm water. As they get older and larger they will start to separate.

Hammerhead Shark And Beautiful Shades Of Blue

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The Unique Hammerhead Shark

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Most of the hammerhead sharks are gray or brownish.

However, the smooth hammerhead shark is olive green or dark gray-brown on the top and white underneath. Their pectoral fins have black tips.

Links to other pages in this site

How Many Teeth Do Sharks Have?
How Long Do Mother Sharks Carry Their Babies?
How Does A Shark Breathe?
Why The Great White Shark Is Endangered?
Where Do Sharks Live?

The basking shark is the second largest shark in the world, only surpassed by the whale shark and, also, is one of the three planktivorous sharks. It is a “kind” shark for divers, despite its size and the impressive mouth that it possesses.

It belongs to the order Lamniformes, to the family Cetorhinidae and the genus Cetorhinus.

Description

The most impressive feature of the basking shark is its mouth, which opens up to 1 meter wide. It has a conical body covered with a layer of mucus, gray or brown skin on the back and white on the belly. Its dorsal and pectoral fins are so large that they can reach 2 meters each and its tail is crescent moon shaped.

It has a conical snout and large gills. Inside its mouth, this shark has several hook-shaped small teeth. Its liver is about 25 percent of its total body weight and is rich in squalene, a substance that helps the shark to float.

Its liver is about 25 percent of its total body weight.

Its weight ranges between 3,000 and 6,000 kilograms, and its length is around 6.7 and 8.8 meters.

Characteristics of the basking shark.
Basking shark – Cetorhinus maximus

Distribution and Habitat

The basking shark inhabits all oceans of the world, but it prefers the subpolar seas and in general cold and temperate waters of the continental shelves. It was recently discovered that it goes as far south as the equator and dwells into warmer waters.

Its habitat changes according to the food availability. In summer it goes to coastal areas to feed abundantly on copepods, but as soon as the winter begins, it migrates to cold water areas. Sometimes it gets close to the coast, and its great body is seen below the surface following concentrations of plankton near the surface.

Basking Shark – Cetorhinus maximus.

Feeding

Like the whale shark and the megamouth shark, the basking shark mainly feeds on plankton, so it is not a common predator. But unlike the other two species, it does not seem to actively seek for food or use the muscles of its head to suck water, instead, it usually swims with its mouth open and catches whatever it goes through. When the water passes through its gills, the spines of the gills rakers separate the plankton from the water. The shark closes the mouth and then pumps the water out through the gills.

The basking shark relies on the guidance of its large olfactory bulbs to detect food. It is a passive eater that can filter around 1,500-2,000 cubic meters of water per hour to obtain sufficient quantities of zooplankton, which also includes fish and small crustaceans, invertebrate animal larvae and fish eggs or larvae.

It feeds near the ocean surface, especially when plankton is abundant. Although it has hundreds of small teeth, it does not use them when feeding.

Behavior

The behavior of the basking shark is still unknown except for some information obtained from the observations. The motto of “basking” was got because it spends a long time feeding under the sun. One theory states that it prefers to feed in surface waters when there is abundant plankton in that part of the ocean, and at the same time it drops the spines of its gills. These are then renewed and so on, in a continuous seasonal process.

During the winter there are no sightings of basking sharks near the surface. Therefore scientists think that they migrate to deeper southern waters until the next summer. During this season many individuals are seen on the coasts of Iceland and northern Europe as they travel there to mate.

Its English name “basking shark,” means “taking the sun”.

The sturdy body and slow movements of the basking shark are not an impediment to jump out of the water trying to shed its parasites. It is also a relatively social animal because sometimes it forms small groups divided according to sex. Sometimes, they can form schools of up to 100 members.

Its English name “basking shark,” which means “taking the sun,” comes from its habit of swimming very close to the surface with the dorsal fin out of the water.

Reproductive Habits

The basking shark is ovoviviparous and reaches sexual maturity when it reaches a particular size; The male can reproduce if it already has a length of 1.5-1.8 meters and the female reaches sexual maturity when it has a length between 4 and 5 meters.

The type of reproduction, it is believed to be ovoviviparity. Fertilization is internal, and the embryos develop within the mother’s body in a yolk sac and without placental attachment. It is very likely that unborn babies practice oophagy.

Researchers are not yet sure of the length of the gestation period. The most accepted theory is that it lasts one year, but can be extended to 2 or 3 years. There is also no accurate knowledge about the number of offspring delivered, but once a pregnant female found had six developing pups inside, so perhaps the number is not very large. Once born, the little ones move away from the mother to start living on their own.

The basking shark gives birth only once every two to four years and its life expectancy is 50 years.

Threats and Conservation

The fishing of this shark has been very frequent for several centuries to obtain and to trade the meat, the oil, the liver, the cartilage and the fins. The oil, liver, and fins are still valued today, and this has caused serious problems for the survival of this shark that the IUCN Red List classifies it as a “Vulnerable” species.

For about 20 years, populations have drastically reduced and have not recovered yet. Fortunately, the situation put some countries on alert, and the species is now under protection in territorial waters of some countries like United States, United Kingdom, and New Zealand. Also, the commercial fishing of this species is banned in many regions.

Sources:

http://www.nefsc.noaa.gov/nefsc/Narragansett/sharks/basking.html

http://www.bbc.co.uk/education/guides/z94hvcw/revision

https://en.wikipedia.org/wiki/Basking_shark

http://www.iucnredlist.org/details/4292/0

http://www.arkive.org/basking-shark/cetorhinus-maximus/

https://www.flmnh.ufl.edu/fish/discover/species-profiles/cetorhinus-maximus

BioExpedition Publishing © 2017.

Basking Shark in the Irish Sea

Goblin Shark – Mitsukurina owstoni

Among all sharks, this species stands out for its unusual appearance characterized by a prominent snout. It is the only living member of the Mitsukurinidae family, and it is often called a “living fossil” since its ancestry goes back to the Cretaceous period and it keeps such primitive characteristics.

It was given a scientific name in honor of two people who collaborated in its discovery in the late nineteenth century: Kakichi Mitsukuri and Alan Owston. It belongs to the order Lamniformes and the genus Mitsukurina.

DESCRIPTION

The goblin shark differs from other shark species by having a flattened snout that protrudes from the top of its head, resembling the blade of a sword. Its jaws are protrusive, and the inside contains 35 to 53 rows of upper teeth and 31 to 62 rows of lower teeth. The length and width of its teeth are variable because those that are near the center of the jaws are longer than those on the back.

Has a flattened snout and its jaws are protrusive.

It has a thin body with a skin covered with dermal denticles. Its blood vessels are very close to the skin, which gives it a pink hue. It has five pairs of gill slits, two small rounded dorsal fins, short and wide pectoral fins, one anal fin smaller than the dorsal fin, and a caudal fin with a poorly developed lower lobe.

It is a medium-sized shark. The length of adults ranges between 3-4 meters, and the weight can reach 200-210 kilograms.

DISTRIBUTION AND HABITAT

Individuals of this species have been found in the Pacific Ocean, in the Indian Ocean, and in the Atlantic, so it is likely to have a global but non-uniform distribution. However, it mainly concentrates in waters of Japan, Australia, New Zealand, Guyana, Suriname, French Guiana, France, Madeira, Portugal, South Africa and the United States.

The sightings of goblin sharks are very rare and indicate that the species lives in waters on continental platforms and slopes, at depths of 1,300-1,370 meters.

FEEDING

The remains in the stomachs of several individuals captured reveal a carnivorous feeding based on teleost fishes, ostracods, squids, crabs, and cephalopods. Garbage and pelagic species have also been found in their bellies. Therefore this shark can swim in depths as well as on shallow waters to find food.

It detects prey by combining its senses of sight, smell, and electro-perception. If it is near the ocean floor and discovers a victim, it observes it from below without moving. It is not a skilled or fast swimmer, so it moves slowly towards its food to avoid being discovered.

The jaws of this shark have the ability to slide forward thanks to specialized joints that at the moment of biting are released from their tense condition and move abruptly and quickly to find the body of the prey.

BEHAVIOR

Although it is an efficient predator, it moves slowly, and that is why its hunting strategy is to wait until the prey is unaware. Their feeding based mainly on migratory fish suggests that many of the activities of this species occur during the nights or mornings.

Another method of finding food is moving the sand once it senses that something is beneath it. Probably the least used sense is the sight because it has tiny eyes.

It does not represent any danger to humans.

REPRODUCTIVE HABITS

There is a lack of information about the reproduction habits of the goblin shark since the sightings have been few and therefore, also the research. The few data available came from individuals caught accidentally and not from observations directly in their habitat.

Researchers believe it is ovoviviparous and migrates to mate or spawn as adult females gather in the east coast of Japan during the spring.

THREATS AND CONSERVATION

As it is rarely seen and captured, the goblin shark status in the Red List of the UICN is “Minor Concern.” Their few known threats are the accidental catch, mainly on the coasts of Japan. Besides, their strange jaws arouse curiosity to collectors who can pay from 1,500 to 4,000 dollars to get one.

Sources:

https://en.wikipedia.org/wiki/Goblin_shark

http://www.iucnredlist.org/details/44565/0

https://www.flmnh.ufl.edu/fish/discover/species-profiles/mitsukurina-owstoni/

http://australianmuseum.net.au/goblin-shark-mitsukurina-owstoni

http://animaldiversity.org/accounts/Mitsukurina_owstoni/

BioExpedition Publishing © 2017.

Megamouth Shark – Megachasma pelagios

The megamouth shark is an exotic species discovered in 1976. It is very unlikely to see, and no one suspected its existence until then, when a new family, genus, and species was created to classify this shark.

It is the most primitive living species of the order Lamniformes but is the smallest shark of those that feed on plankton. He is a member of the mentioned order, the family, Megachasmidae, and the genus Megachasma.

DESCRIPTION

Its large head and the huge mouth that indicates its name are the main features that help to identify this species undoubtedly. It has a length of 4 – 5 meters and weighs about 800 kilograms. The color of its cylindrical and flaccid body is usually black or dark brown on the dorsal area and pale gray in the ventral region. Its skin also has dermal denticles as other shark species.

It is the most primitive living species of the order Lamniformes.

It is not a skilled swimmer. Their dorsal fins are small and the second is half the size of the first one. It has pectoral fins smaller than the size of its head, and it has an asymmetrical caudal fin with a long upper lobe.

It has tiny eyes, five pairs of long gill slits, and a short, rounded snout. Inside the mouth has a tongue covered with mucosa and about 50 rows of small hooked teeth but only uses the first three rows. Around its mouth, it has photophores which glow and appear to act as baits for small fish or plankton.

DISTRIBUTION AND HABITAT

Its distribution and habitat are still uncertain, but a few sightings in areas of the Pacific, Indian and Atlantic Oceans are on record; and since its discovery in Hawaii, only 55 more sightings have been registered in countries such as Brazil, Senegal, the Philippines and Indonesia. The first discoveries were on the coasts of California, Japan, and Australia, in addition to the Hawaiian islands.

It is an inhabitant of the deep waters (between 150 and 1,000 meters) that likes moderate and warm temperatures.

FEEDING

It is one of the three species of sharks that are fed by filtration of plankton. Its diet may include shrimp, copepods, and pelagic jellyfish.

There are few details about its form of feeding, but most scientists think that it swims slowly through the plankton concentrations and opens its huge mouth to suck the water, then lower the jaws, retract and filter the planktonic organisms by expelling the water through its gills.

BEHAVIOR

The limited observations of this shark provide little information but render an overview. It is known to exhibit a behavior similar to that of other benthic fishes, and it does not tolerate the disturbances external to the ocean, perhaps that is the reason for its late discovery.

This shark is a vertical migrant during 24-hour cycles.

In the early 1990s, a tag was placed on megamouth shark to monitor for two days its behavior in the coasts of California, United States. As the sun start shining, it swam to a depth of 120-160 meters but began to ascend as the sun began to hide. During the night it stayed near the surface at depths between 12 and 25 meters. The research gave evidence that this shark is a vertical migrant during 24-hour cycles, spends days in deep water and nights in mid-depth waters.

Probably, this pattern of movement is related to the behavior in the columns of water of his favorite prey, which he follows to feed on.

REPRODUCTIVE HABITS

Sexual maturity occurs when the shark reaches a length of about 4 meters. Fertilization is internal, so the male inserts its claspers into the female oviduct to transfer the sperm.

The megamouth shark is an ovoviviparous species. Therefore the pups are developed inside the mother’s body until their birth. The genders separate and look the same as adults.

The ovaries of the female are similar to those species that practice oophagy, and this means that presumably the offspring of this shark also feed on other eggs inside the body of their mother.

THREATS AND CONSERVATION

The fact that this shark is hard to observe implies a problem in its research and the detection of the type and severity of its threats. In fact, the International Union for the Conservation of Nature does not yet have enough data to classify this species.

So far, its greatest threat is bycatch resulting from commercial fishing activities. On the other hand, some museums welcome deceased individuals for its exhibition. So far proper conservation measures have not been taken.

Sources:

http://wwf.panda.org/what_we_do/endangered_species/sharks/pelagic_sharks/

http://www.arkive.org/megamouth-shark/megachasma-pelagios/

http://www.iucnredlist.org/details/39338/0

https://en.wikipedia.org/wiki/Megamouth_shark

http://animaldiversity.org/accounts/Megachasma_pelagios/

BioExpedition Publishing © 2017.