The basking shark, “cetorhinus maximus,” are the world’s second largest fish after the whale shark. The species is a coastal-pelagic shark, found world wide in temperate waters, though they prefer waters between (46 and 57 F). They get the name “basking shark” from one of its unique behavioral attributes – they are usually observed feeding, and therefore appearing to be basking. A cosmopolitan species, it is found all over the world in any temperate ocean. The slow moving, harmless filter feeder (like other sharks) has a number of distinctive behavioral attributes that distinguish it from other types of sharks of its size.
ABOUT THE BASKING SHARK
The basking shark normally reaches the 20-26 feet. However, there have been rare reports of them reaching over 33 feet in length. There are only a few other sharks of this distinguished size, and they have been mistaken for great white sharks, even though they are vastly different behaviorally and in many other distinct ways, because they are roughly as large share the same lamniform body plan. Some other characteristics of the basking shark include a strongly-keeled caudal peuncle, highly-textured skin covered in placiod plates and a lunate cadual fin.
DISTINCTIVE BASKING SHARK BEHAVIORS, INCLUDING FEEDING TRAITS
Before studies in 2003, scientists thought that basking sharks hibernated. But those studies have found instead that they are active throughout the year. In the winter the sharks dive to deeper depths to feed on deep water plankton. Scientists also found that they shed and renew their grillrakers on an ongoing basis. These sharks are slow moving and do not avoid approaching boats. They are harmless to humans and will not be attracted to chum. Their social behavior is thought to follow visual clues. Although their eyes are small they are fully developed and can visually inspect boats.
Basking sharks have several types of distinctive behaviors that are associated with feeding characteristics. It used to be thought that the basking shark’s teeth were useless, but it is now known that they are important to help them feed on eggs in the utero. Although the basking shark is slow, it has been reported to jump completely out of the water. Scientists believe that this could be done to get rid of parasites deal with other skin or physical conditions.
The basking shark is a passive filter feeder and it filters zooplankton, small fish and other small invertebrates from up to 2,000 tons of water per hour. They follow groups of plankton I they can find them. Unlike other filter feeders the basking shark lacks the ability to suck or pump water their gills they can only rely on water pushed through their gills while swimming. These sharks have few predators but tiger sharks and orca whales have been known to feed on them. The aforementioned lampreys are often seen attached to them but they rarely cut through the shark’s skin.
BREEDING, REPRODUCTION AND LITTLE UNDERSTOOD BEHAVIOR
Basking sharks have several knowm mating and reproductive behaviors. This type of shark, unlike great whites and others of its size (and that are known to be agressive predators) they are social animals and form schools separated by sex. Basking sharks are referred to as ovoviparous and the females are known to seek out shallow water to give birth.
In addition to other knonw and understood mating and breeding behaviors, the basking sharks have several other types that that are not well understood and may be courtship or other breeding behaviors. Aerial photographs have shown a variety of schooling patterns, including milling, cartwheel and echelon, formations. While the function of these aggregations remains unknown, they may represent group courtship behavior.
Documentation has found the basking sharks in tight circles slowly swimming clockwise. Basking sharks have previously been described engaged in elasmobranch reproduction, which includes “parallel swimming,” possible “pectoral biting,” “nudging,” in addition to other behaviors, including nose-to-tail swimming, and cloas and flank approaches (swimming together), involving echelon swimming, rostral contact or proximity with the gill, pectoral fin, vent, and dorsum.
Various swimming behaviors involving persistent physical closeness between two or more sharks and repeated circling behavior in a tight and specific area over a period of time exceeding 5 minutes indicates that this type of behavior might be the first actual well-documented group courtship activities in basking sharks. What it means to marine biology and the study of sharks is that there is still a lot left to be learned about them, particularly about their behaviors, if there are still new ones being discovered and documented, and particularly ones that need further explanation.
The basking shark due to its low resilience, over fishing and lack of fear of humans is on the decline. But because of this new information on new and little understood behaviors, there might be things that can be done to intervene on behalf of this species to lead to its health and resilience in the future. Perhaps attempts to further understand the species, including all of its unique behavior traits, will add to the health of and preservation of the basking shark for further generations of scientists and marine biologists.