The basking shark (Cetorhinus maximus) is a giant shark. In fact, it is the second-largest shark following the whale shark known to man. This shark is a plankton-eater, and one of the three shark species known to feed on planktons. The others include the whale shark and megamouth shark.
A full-grown basking shark will typically reach a length of 26 feet (7.9 m). However, not minding the large intimidating size, the basking shark is not aggressive to humans in any way.
The common name “basking shark” came from the shark’s habit of feeding near the surface of the sea. Thus making the shark appear to be basking in the sun.
This shark is a widely distributed migratory species found around the world in temperate oceans. There is a lot of things to learn about this gentle giant shark. And, this page brings to you all the facts you need to know about the basking shark.
Scientific Naming of the Basking Shark
The basking shark is a member of the family Cetorhinidae and the only member of its family still in existence. However, its order Lamniformes includes the mackerel shark.
This shark is from the genus Cetorhinus Derived from Greek words ketos and rhinos. Whereby, ketos means marine monster or whale and rhinos means nose. Its species name is maximus from Latin meaning greatest. Jonah Ernst Gunnerus was the first to describe this shark species as Cetorhinus maximus using an individual discovered in Norway.
Apart from basking shark, other common names to identify this shark species includes elephant shark, bone shark, Sunfish, and **sailfish. Similarly, in Orkney islands basking sharks go by the common name *hoe-mother* which implies “the mother of pickled dogfish”.
Habitat and Distribution Range
Basking sharks are migratory fish species, as such, they inhabit a wide range of habitat. Although, they prefer the cold and temperate regions of the oceans around the world. This shark occurs along the continental shelves and occasionally venture into brackish waters.
The basking shark frequently swims to the surface of the water where they occur. However, they can occur to a depth of 2,990 feet (910 m). As temperate water inhabiting fish, they prefer a temperature range of 46 to 58 F (8 to 14.5 C). But, of recent, they have been confirmed to swim across the equatorial waters which tends to be warmer.
This species of shark stays close to land and also swim to bays with narrow openings. Their migration follows the concentration of planktons in the water column, which makes the shark often seen at the surface. More so, plankton concentration may vary according to the season, leading basking sharks to various habitats.
Basking Shark Description and Appearance
It is easy to recognize the basking shark while it is near the sea surface. This is due to its cavernous mouth and obvious gill slits. It has a snout conical in shape and five gills slits which tend to circle round its head. And, each of the gill slits contains thousands of well-developed gill rakers that help the shark filter in planktons as meals.
The eyes of the basking shark are small compared to the shark’s overall size. Similarly, the teeth are small and hooked and many. However, it is only three to four rows of teeth on the upper jaw and six to seven rows in the lower jaw that functions. An impressive feature of the basking shark is its ability to expand its jaws to open its mouth up to 3.3 feet (1 m) wide.
The basking shark has a unique appearance noted by its crescent moon-shaped tail and fins which reaches a length of around two meters. This shark has a skin generally gray to brown in color covered in placoid cells with a layer of mucus and somewhat pale on the belly side. And it has the typical body plan of lamniformes.
The dorsal fin of larger basking shark individuals may tend to flop one side while above the water surface. An adult basking shark will attain an average length of 26 feet (7.9 m). Although some individuals will grow to a length of 30 to 33 feet ( 9 to 10 m), large-scale fishing over the years made individuals of such sizes rare.
On the other hand, the average weight of this shark species is about 4.65 tons. And, 25% of the shark’s overall body weight is accounted for by the liver which runs the entire length of the abdominal cavity. The liver is rich in squalene which helps the shark stay afloat and in energy storage for an extended period.
Typical Basking Shark Behavior
Basking sharks are active all year-round, as they do not hibernate. They would tend to swim to deeper parts of the ocean during the winter. As such, they get down to depths of about 3000 feet (900 m) making vertical movements in line with feeding on overwintering zooplanktons.
This shark is generally slow-moving and peaceful. However, it is capable of “breaching” which means that a basking shark not minding its size can still jump entirely out of water. There is no evidence found why this shark jump from the water, although experts speculate it to be behavioral interactions that may involve an attempt to dislodge parasites or commensals.
Basking sharks would not attempt to escape from approaching boats. More so, they would not respond to a chum (a mixture of fish parts and blood dropped into the water to attract predator sharks).
They can move thousands of kilometers during the winter or summer in search of areas with rich zooplankton concentration which mostly occur along ocean fronts.
Interaction with Own Species
Basking sharks are mostly solitary, however in summer months particularly they tend to assemble in areas with a dense concentration of zooplankton. Here, they would engage in certain social behaviors. As such, they can form shoals segregated by sex, thus, it could be all-male or all-female groups. Their social group is usually in a small number of about 3 or 4 members. Although, there are reports of up to 100 individuals.
Sometimes, these small schools swim nose to tail in circles as observed in the school in the Bay of Fundy and the Hebrides. There has been a study of the social behaviors of the basking shark during the summer months and believed to represent courtship.
Escaping Predators
Basking sharks are very large fishes and rarely have predators. However, there are reports of White sharks scavenging on the remains of these sharks. Even more, off California and New Zealand, killer whales have been observed feeding on basking sharks.
Also, lampreys would often attach to the basking shark, although it is unlikely that they are able to cut through the thick skin of the shark.
Basking Sharks Feeding Habits
The Basking shark is planktivorous, as such it feeds mainly on planktons along with the megamouth shark and the whale shark. Hence, this shark is not a common predator. It will often swim with its mouth wide open trapping whatever food that enters. Then, when they get to the gills, the spines of the gill rakers would filter in the planktons while filtering out the water. The shark closes its mouth to pump out water through its gills.
Basking sharks feed near the sea surface, especially where there is a concentration of planktons. This shark is a filter-feeder, though it has hundreds of teeth, it does not feed with them. thus, the gill rakers play more role in the feeding process of this shark.
To detect food, this shark relies on the impulse of its large olfactory bulbs. It does not engage in the active seeking of food nor does it make use of the muscles on its head to suck water. Instead, the basking would leave its mouth open as it swims to let food go through. This shark is also a passive eater and can filter volumes of water around 1500 to 2000 cubic meters in an hour to get a sufficient quantity of plankton. The food materials filtered also include small crustaceans and fish, larvae of invertebrates and fish eggs.
Mating and Reproduction
The basking shark is an ovoviviparous species, hence, it develops its embryos on a yolk sac that has no placental connection. Their teeth which seem to be useless play a role here in “oophagy” which is a feeding process where the developing embryos feed on the unfertilized eggs of the mother. Surprisingly, it is only the right ovary of the female basking shark that tends to function, and it is not yet clear why the other one does not seem to function.
Although not clear, this shark would gestate for more than a year. There are speculations that this process might take up to 2 – 3 years. Afterward, they give birth to small numbers of young sharks. Basking sharks would mature within the age range of 6 and 13 years, usually the age they grow to a size of 15 to 20 feet (4.6 to 6 m) at least as speculated.
It is thought that basking sharks mate during the early summer as the females swim to shallow waters. Here, they form sex-segregated schools and swim in a nose-to-tail manner circling around. This behavior is believed to be a form of courtship.
There is not much known about the reproduction of basking sharks and their life cycle. Thus, most of the information bases on guesses from experts. As such, there also is an estimate of the shark’s lifespan to be about 50 years.
Basking Sharks and Human Interactions
In the past times, basking sharks were the center of fishing for various commercial purposes which includes flesh for food, skin for leather, and liver for oil due to its high squalene content. However, while there is a ban placed on the fishing of this gentle giant in most countries of the world today, the few places it is still prone to capture are China and Japan.
These places it is mainly sought for its fins used for shark fin soup, locally as an aphrodisiac and health food in Japan, and traditional medicine in China gotten from parts such as cartilage. Also, the shark’s oil serves as an ingredient in making cosmetics.
This shark is mostly placid in nature and swims slowly. Thus, a basking shark would not naturally pose any threat to humans even with their large intimidating size. However, every creature when threatened tends to react aggressively. Such applies to the basking shark, hence be cautious of its dangerous side.
Basking sharks would not attempt to get away from approaching boats and divers. Instead, they are tolerant of all and sometimes may circle divers making this species an important draw for dive tourism in places where such activity is common.
Threats and Conservation
Cetorhinus maximus was once an abundant species in nature, however, human activities which include direct fishing and by-catching in trawl nets serve as the major threat to the population of this shark. As such, this shark is now confirmed scarce in many regions where it was once occurring in large amounts.
Currently, the IUCN Red List states that the basking shark (Cetorhinus maximus) is Endangered (EN).
Many conservation actions are now in place to save this shark species from extinction. For instance, there is a regulation that requires the release of live basking shark caught by mistake across many states.
Can Basking Shark Make a Good Aquarium Pet?
No, there is no need thinking about it. This shark would not in any way make a good aquarium pet. The enormous size of this shark species alone is enough reason why the shark won’t make a good pet.
More so, the skin of basking sharks has dermal denticles (scale) tooth-like in appearance projecting to all directions and contact with this will lead to severe cuts and scratches.
Note that even while the basking shark is calm and tolerant, it is not a domesticated fish. Even more, many government law does not allow the captive keeping of this fish species as part of the conservation action. And, still, protect them in their natural habitat.
Amazing Basking Shark Facts at a Glance
1. Basking Shark Mistaken for a Sea Serpent
Tales from the ancient times reports the sighting of sea serpents and monsters. But, more recent findings show that those were basking shark sightings. Of course, fishermen who saw the giant shark could not believe it to be a fish due to its unusual physical appearance. Thus, they reported seeing a large beast of the sea.
2. Interestingly, Basking Sharks Can Breach
This shark species grows enormously large, yet this does not prevent it from jumping out of the water in a process known as breaching.
3. Basking Sharks are the Second-largest Fish Species in the World
After the whale shark, basking sharks (Cetorhinus maximus) comes as the second-largest fish in the world.
4. It has Small and Numerous Teeth
The teeth of the basking are small and aboutn100 hundred in a row. This is more than any other fish species. Also, the teeth possess single conical cusp curved backward. They look alike in both the upper and lower jaws.
5. The Basking Shark Can Open its Mouth Over 3 feet Wide
The largemouth of the basking shark interestingly opens as wide as 3 feet (1 m).
6. Among the 3 Plankton-eating Sharks
There are only three sharks known to feed on planktons and the basking shark is one. The others include the whale shark and megamouth shark.
7. Basking Sharks are Peaceful Fish Species
This shark is not aggressive and tolerates being approached by humans in boats and even divers.
8. Only the Liver Make Up 25% of the Shark’s Total Body Weight
The liver of the basking shark is so large making up twenty-five percent of the total body weight of the shark. But then, it also accounts for the shark’s buoyancy, which is the ability to remain afloat.
9. Basking Sharks Change Their Snout
As juveniles, basking sharks have a snout that appears like a hook. However, after they attain one year of age, the snout changes shape.
10. The Basking Shark is Now a Protected Species
Following the massive decline in the population of basking sharks, many countries around the world took conservation actions. Thus, advocating for the protection of this Endangered species. However, there is no such law applicable in China and Japan, as such still hunted in these places.
Conclusion
Basking sharks are interesting fish species as described on this page. As we know already, they are endangered species as such to keep this shark in existence, there is a need to take the conservation laws seriously.
Further Reading
- Basking Shark Wikipedia (edited 31 January 2020), Wikipedia. Online here
- Cetorhinus maximus (Basking Shark) IUCN Red List of threatened species. Online here
- “Interesting facts about basking sharks”, justfunfacts. Online here
- “Basking Shark – Description, Habitat, Image, Diet, and Interesting Facts”. Online here
- “Basking Shark, Cetorhinus maximus, marinebio. Online here