Introduction

The legendary great white shark is a cartilaginous fish that has caused fear and admiration for many years. It is considered one of the biggest predators of the oceans and the fiercest, but there is more imagination than truth in this sentence. His reputation as a “man-eater” is also far from reality.

The white shark is a member of the class Chondrichthyes, the subclass Elasmobranchii, the order Lamniformes, the family Lamnidae and the genus Carcharodon.

DESCRIPTION

The body of the white shark is robust and fusiform, about 4-7 meters in length but the average is 6 meters. Its weight is between 3,000 and 3,400 kilograms. Adult females reach dimensions greater than males, which are usually 2 meters smaller.

Their sense of smell is very sensitive, which facilitates the detection of prey at a great distance.

It has a narrow pointed snout, two pectoral fins and a first dorsal fin with a triangle shape. The caudal fin is crescent-shaped, and its upper and lower lobe are long and of very similar size, almost symmetrical. The mouth measures 0.9 to 1.2 meters wide; Is provided with several rows of sharp and serrated triangular teeth, that the shark changes several times throughout his life. It has small onyx eyes and nostrils towards the end of the snout.

It exhibits discoloration of the body, because while the back is gray or blue, the lower area is lighter. This characteristic gives an advantage when hunting because preys do not notice the figure of the shark, which is confused with the bottom of the ocean.

Their sense of smell is very sensitive, which facilitates the detection of prey at a great distance, and together with the Lorenzini ampoules which detect electric fields of moving animals make them efficient predators.

Facts on video

DISTRIBUTION AND HABITAT.

The distribution area of the great white shark is very extended; It ranges from the latitudes 60 ° north to 60 ° south and can be found in tropical coastal waters as well as temperate and even cold. In general, the temperature of the water that inhabits oscillates between 12 ° and 24 ° Celsius.

It is commonly found on the coasts of North America from Newfoundland to southern Mexico in the Atlantic Ocean and from Alaska to southern Mexico in the Pacific. Outside of the American continent, the great white shark dwells mainly the waters of South Africa, the Mediterranean Sea, Japan, and Oceania. There is a substantial population in the Dyer Island in South Africa, and that is why there is a common place for research about their life.

Their habitats include coasts and continental and insular platforms whose waters do not surpass 1,875 meters of depth. In the open ocean, it inhabits to depths of up to 1,200 meters. It is an epipelagic shark that has been seen close to the shore on many occasions, but it is not an eminently coastal species.

Great White Shark – Carcharodon carcharias.

FEEDING

The diet of this shark species is, of course, carnivorous. However, it does not usually feed on large species, but on smaller animals such as squids, rays, and other fish. Adult individuals also include other sharks, seals, sea lions, dolphins and whale corpses. They sometimes catch turtles and seabirds to feed on them. They have a clear preference for fat-rich prey.

They have different hunting strategies depending on the target victim and the size of the species. The most usual approach is that, once they detect by electroreception their possible food, they locate below and then stealthily swim vertically. Once closer, they inflict a deadly bite and wait for the animal to bleed and die and then eat it. If the prey survives that, they try to hold it with their lower teeth while the upper tear the tissues. The most common forms to die of their preys are decapitation, mutilation, and bleeding.

BEHAVIOR

The great white shark is a fish mostly solitary although it can reunite with others of its same species. He has been seen a few times accompanied by a female or a male and even in small groups. In their groups, it is likely that there is hierarchical dominance, and the females are in the lead, but among all, large individuals dominate the small ones, and the residents of the group for a long time dominate the newcomers.

This shark is active both day and night. Interestingly, they jump out of the water sometimes to look the surrounding and look for prey. They are not aggressive with their own species, but if they feel threatened, they may bite his antagonist as a warning.

Most people expressly fear the great white shark and consider it a man-eater predator. Definitively, it is a powerful, aggressive and efficient predator, but it has no preference for humans. The attacks usually happen because of the shark confusion of a person with prey, and as a consequence, they give a “test bite,” but it is unlikely that it keeps eating once it finds that it is not its usual food.

REPRODUCTIVE HABITS

Males sexually mature about nine years old, but females mature between 14 and 16 years. This species is slow growing, late maturing and relatively long life.

Their reproduction is ovoviviparous. Bites on the flanks, backs and pectoral fins of females indicate that males exert “soft” aggression before and during mating. Males fertilize the eggs internally, inserting their claspers into the female oviduct so that eggs develop inside their body. Before birth, developed embryos presumably practice oophagy.

The gestation period lasts between 12 and 18 months, after which the female gives birth between 2 to 10 live offspring measuring more than 1 meter long. Female gives birth every 2 or 3 years.

THREATS AND CONSERVATION

The great white shark is at the top of the food chain, and except for killer whales, whales, and humans, it does not have predators. However, the Red List of the International Union for Conservation of Nature (IUCN) has classified it as a “Vulnerable” species, since overfishing and by-catch have led to a decrease in the number of individuals, as they have a low reproduction rate.

Some countries such as the United States, South Africa, Namibia, Malta and Australia protect the great white shark within their oceans, but it is still a feared and misunderstood fish. Therefore the conservation efforts do not have enough reach and impact.

Great White Shark Infographic!

(Click for expand)

Sources:

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

http://www.iucnredlist.org/details/3855/0

World of Animals Magazine. Issue 1. Imagine publishing.

World of Animals, Book of Predators. Imagine publishing. 2014

http://www.arkive.org/great-white-shark/carcharodon-carcharias/

http://sharkopedia.discovery.com/types-of-sharks/great-white-shark/#top-10-greatest-great-white-videos

BioExpedition Publishing © 2017.

The whale shark is a giant of the oceans: the dimensions of its body gives it the title of the largest fish in the world and therefore, also the biggest shark.

It is the only member of the genus Rhincodon. It belongs to the order Orectolobiformes and the family Rhincodontidae.

DESCRIPTION

This shark shares the name of the cetaceans because of its massive size, but it is a fish that can measure up to 20 meters long, although it has an average size between 9 and 12 meters long. It weighs over 12,500 kilograms. Its fusiform body is wide in the middle area and narrows in the tail and head that is wide and flat, and it has two small eyes on the front. Its mouth, located towards the end of the snout, can open about 1.5 meters. Inside there are 300-350 rows of teeth and ten pairs of useful pads to filter the food.

It has one pair of nostrils at the tip of the snout, lack of circumnarial grooves but it has rudimentary beards. It has five pairs of gill slits on each side of the head and spiracles behind the eyes. Like many pelagic sharks, it has one pair of dorsal fins (one larger than the other) and one pair of pectoral fins as well as a caudal fin.

The skin of the whale shark has a blue-gray coloration on the back and white in the belly. The upper area has light spots that form unique patterns in each shark.

DISTRIBUTION AND HABITAT

The extensive distribution of this pelagic species covers all the temperate and tropical seas of the world except the Mediterranean Sea. They inhabit waters in the latitudes between 30 ° north and 35 ° south in countries like Mexico, Belize, Ecuador, South Africa, Australia and the Philippines.

This shark inhabits both deep waters and shallow waters with temperatures between 21 ° and 30 ° C but tolerates water up to 3 ° C degrees in some cases. Their favorite habitats are coastal areas with abundant food.

Whale shark – Rhincodon typus.

FEEDING

Fortunately for many animal species (including humans), the natural food of the large whale shark is mainly plankton, although occasionally includes other small animals such as krill, jellyfishes, sardines, anchovies, mackerels, squids, and crabs, as long as they are small.

Their feeding method consists of suction and filtration; Is called “passive feeding” since there is little pumping and muscular activity in the gills while they eat. While swimming, the shark tends to keep its mouth open to access the food and suck it hard. Once inside, the whale shark closes its mouth, and the plankton gets trapped in its filtering organs, and at the same time, they expel the water through the gills. The reason for the presence of teeth is unknown because they do not use them for eating.

It can actively feed when it opens and closes its jaws to catch the food at any given time, and passively when it keeps its mouth open as it swims forward and the food gets inwards.

BEHAVIOR

It is one of the most docile sharks that exist and does not present any danger to humans. They even allow divers to have contact with them despite the scientists’ disapproval of this activity.

It is an intelligent animal who demonstrates the ability to learn. Captive sharks in aquariums exhibit changes in their behavior when humans come to feed them as they begin to swim in circles. Observations indicate that they sometimes perform a cough-like activity, presumably to clean their filter pads.

They usually swim unaccompanied by other sharks, but on certain occasions (feeding and mating) they travel long distances together. It is also possible that they modify their swimming patterns according to the environmental conditions.

Whale shark with remoras.

REPRODUCTIVE HABITS

Some scientists think that they have a polygamous mating system, but this is not confirmed. Except for some research, there is not much information about whale shark mating and reproduction and birth has never been observed.

They reproduce through ovoviviparity and females deliver live pups that reach a length between 40 and 60 centimeters. The number of offspring is not determined, but apparently, they are many because during the 90 s a female captured had about 300 fetuses inside. The pups are not born all at the same time; the female stores the sperm of a male and can develop new offspring after some time.

Males and females reach sexual maturity around 30 years old.

Facts on video

THREATS AND CONSERVATION

Despite their size, they are not free from predators in their natural habitat. Orcas, blue sharks, white sharks and blue marlin attack mainly young individuals who are still vulnerable because of their small size. On the other hand, humans considerably contribute to the status this shark has on the IUCN Red List: Vulnerable. Their meat is valued in Asia, and their fins are sold to elaborate soup with supposed medicinal and aphrodisiac properties.

The conservation efforts for this species are still incipients although some countries are already protecting them, for example, countries, like the Philippines, and Australia, regulate the activities related to whale sharks. Their capture is banned in that Asian country, and the Australian Department of Conservation is responsible for monitoring the tourist visits to the whale sharks.

 Whale Shark Infographic!

(Click for expand)

Sources:

http://www.iucnredlist.org/details/19488/0

http://www.arkive.org/whale-shark/rhincodon-typus/

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

http://www.worldwildlife.org/species/whale-shark

http://animaldiversity.org/accounts/Rhincodon_typus/

BioExpedition Publishing © 2017.

Some shark species are going extinct because of excessive human fishing and predation.

People kill sharks for trading, sports, medicine, meals or just because they are afraid of sharks.

Sharks have been around for more than 400 million years, and now after all this time, overfishing is dramatically reducing the population of some shark species.

Links to other pages in this site

Where Do Tiger Sharks Live?
How Many Years Does A Shark Live For?
What Are The Tiger Shark Enemies?
What Kind Of Skin Do Sharks Have?
How Long Do Sharks Live?

The great white shark was added to the endangered list because its population has dropped due to the unregulated trade and excessive hunting.

The great white shark is the top predator of the ocean, and adults have no threats in the seas. However, humans kill a large number of white sharks every year to get their teeth and jaws for trading, their meat for eating and their fins for remedies.

Links to other pages in this site

Why Sharks Attack Humans?
How Many Teeth Does A Great White Shark Have?
How Does A Shark Breathe?
Why Are People Afraid Of Sharks?
How Many Years Does A Shark Live For?

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 2007

Basking Shark Interesting Video

Basking Shark Video