---
title: "What the sources say about the Basking Shark | AnimalTracks.wiki"
description: "42 claims from the Basking Shark profile, each beside the words of the source that backs it."
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---

# What the sources say about the Basking Shark (*Cetorhinus maximus*)

> 42 claims from the Basking Shark profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Basking Shark](https://animaltracks.wiki/animals/basking-shark/)

## Basking Shark, Cetorhinus maximus. Florida Museum of Natural History, Discover Fishes.

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

| The page says | The source says |
| :--- | :--- |
| The second-largest fish on Earth, filtering up to 2,000 tons of seawater an hour through its gills to scoop up zooplankton. | This slow-moving migratory shark is the second largest fish, growing as long as 40 feet and weighing over 5 tons. It is often sighted swimming close to the surface, huge mouth open, filtering 2,000 tons of seawater per hour over its complicated gills to scoop up zooplankton. (note: "up to" from the body's 'can strain up to 2000 tons') |
| Arctic and Temperate Seas Worldwide, Inshore to Offshore | The basking shark is a coastal-pelagic species found throughout the world's arctic and temperate waters. ... The basking shark is typically seen swimming slowly at the surface, mouth agape in open water near shore. This species is known to enter bays and estuaries as well as venturing offshore. |
| Planktivore (Zooplankton: Small Crustaceans, Larvae, Fish Eggs) | These sharks feed along areas that contain high densities of large zooplankton (i.e., small crustaceans, invertebrate larvae, and fish eggs and larvae). |
| Enormous Filter-Feeding Mouth & Up to 2,000 Tons of Water an Hour | Its enormous mouth extends past the small eyes and contains many small, hooked teeth. ... The basking shark's gill rakers can strain up to 2000 tons of water per hour. |
| Up to 2,000 Tons an Hour | The basking shark's gill rakers can strain up to 2000 tons of water per hour. (note: heading) |
| the second-largest fish alive, behind only the whale shark | Second only to the whale shark (Rhincodon typus) in size (note: 'second-largest' is the page's 'second only to the whale shark in size') |
| It can grow as long as 12 meters (40 feet) and weigh over 5 tons | growing as long as 40 feet and weighing over 5 tons (note: 12 m from the source's 40 feet (the page's own conversion elsewhere)) |
| the average adult measures 6.7 to 8.8 meters (22 to 29 feet) | The average adult length is 22-29 feet (6.7-8.8 m). |
| Its enormous mouth extends back past its small eyes. | Its enormous mouth extends past the small eyes |
| Its large gill slits nearly encircle its head, and inside them sit gill rakers, strainers that can sift up to 2,000 tons of seawater an hour. | Food is strained from the water by gill rakers located in the gill slits. The basking shark's gill rakers can strain up to 2000 tons of water per hour. |
| They catch zooplankton, tiny drifting animals such as small crustaceans, larvae and fish eggs. | These sharks feed along areas that contain high densities of large zooplankton (i.e., small crustaceans, invertebrate larvae, and fish eggs and larvae). (note: 'tiny drifting animals' defines zooplankton) |
| Of the three big filter-feeding sharks, the basking shark is the only one that relies solely on swimming to push water through its mouth. The whale shark and the megamouth shark help the process along by sucking or pumping water in. | the basking shark is one of three species of large, filter-feeding sharks. However, the basking shark is the only one that relies solely on the passive flow of water through its pharynx by swimming. ... The whale shark and megamouth shark assist the process by suction or actively pumping water into their pharynxes. |
| Its liver can make up 25% of its body weight. | The basking shark has a very large liver that accounts for up to 25% of its body weight. |
| The liver is high in squalene, a low-density chemical that helps give the shark near-neutral buoyancy, meaning it neither sinks nor rises easily. | The liver is high in squalene, a low-density hydrocarbon that helps give the shark near-neutral buoyancy. (note: 'meaning it neither sinks nor rises easily' defines near-neutral buoyancy; 'chemical' for hydrocarbon) |
| Basking sharks are found in arctic and temperate waters around the world, and are usually seen near shore, though they also venture offshore. | The basking shark is a coastal-pelagic species found throughout the world's arctic and temperate waters. ... The basking shark is typically seen swimming slowly at the surface, mouth agape in open water near shore. This species is known to enter bays and estuaries as well as venturing offshore. |
| Slow to Grow | The basking shark is an extremely slow-growing species (note: heading) |
| The basking shark grows extremely slowly and may reach 5 to 6 meters (16 to 20 feet) before it matures. | The basking shark is an extremely slow-growing species and may grow to 16-20 feet (5-6 m) before becoming mature. |
| Females are estimated to mature at 12 to 16 years old | It has been estimated that females reach sexual maturity between 12-16 years. |
| pregnancy lasts three years or longer | The gestation period is 3 years or longer. |
| Slow growth, late maturity and long pregnancies make the species vulnerable to overfishing. | basking sharks are vulnerable to overfishing for several reasons. They have a lengthy maturation time, slow growth rate and a long gestation period. |
| A basking shark is generally no danger to people. Its skin, though, is extremely rough | Basking sharks are passive and no danger to humans in general, but they are large animals and their skin is extremely rough |
| its large dermal denticles, the tooth-like scales in shark skin, have been known to injure divers and scientists. | its large dermal denticles have been known to inflict damage on divers and scientists (note: 'the tooth-like scales in shark skin' defines dermal denticles) |
| Many people have seen basking sharks leap from the water, and the reason is not fully understood. | Many people have witnessed individual sharks leaping from the water. This phenomenon is not fully understood |
| Some believe a jump may help a shark get rid of parasites and hitchhikers such as remoras and sea lampreys. A lamprey cannot cut through the shark's armored skin, but it may irritate the shark enough to set off a reaction like jumping. | some believe the shark may be trying to rid itself of parasites or commensals such as remoras and especially sea lampreys (Petramyzon marinus), which are often seen attached to the skin of the basking shark. The lamprey cannot cut through the denticle-armored skin, but they may be enough of an irritant to cause a reaction like jumping (note: 'hitchhikers' for commensals) |
| A basking shark (Cetorhinus maximus) swims slowly with its huge mouth open, filtering up to 2,000 tons of seawater an hour. | This slow-moving migratory shark is the second largest fish, growing as long as 40 feet and weighing over 5 tons. It is often sighted swimming close to the surface, huge mouth open, filtering 2,000 tons of seawater per hour (note: "up to" from the page's 'gill rakers can strain up to 2000 tons of water per hour') |
| Gill rakers inside its large gill slits strain out zooplankton, such as small crustaceans, larvae and fish eggs, as the water passes through. | Food is strained from the water by gill rakers located in the gill slits. ... These sharks feed along areas that contain high densities of large zooplankton (i.e., small crustaceans, invertebrate larvae, and fish eggs and larvae). |
| Not usually. Basking sharks are not considered dangerous to people who simply watch them, and they generally tolerate divers and boats. Their size and power still deserve respect, and their skin is best not touched: its large dermal denticles have been known to injure divers and scientists. | Basking sharks are not considered dangerous to the passive observer and are generally tolerant of divers and boats. Despite this, its sheer size and power must be respected (there are reports of sharks attacking boats after being harpooned). In addition, contact with its skin should be avoided, as its large dermal denticles have been known to inflict damage on divers and scientists (note: 'Not usually' answers the question within 'not considered dangerous to the passive observer') |
| It is not fully understood. Some believe leaping may help a shark get rid of parasites and hitchhikers such as remoras and sea lampreys. A lamprey cannot cut through the shark's armored skin, but it may irritate the shark enough to set off a jump. | This phenomenon is not fully understood but some believe the shark may be trying to rid itself of parasites or commensals such as remoras and especially sea lampreys (Petramyzon marinus) ... The lamprey cannot cut through the denticle-armored skin, but they may be enough of an irritant to cause a reaction like jumping |

## Cetorhinus maximus. AnAge: The Animal Ageing and Longevity Database.

https://genomics.senescence.info/species/entry.php?species=Cetorhinus_maximus

| The page says | The source says |
| :--- | :--- |
| The longest lifespan recorded for a wild basking shark is 32 years. | Maximum longevity 32 years (wild) (note: 'longest recorded' is AnAge's 'maximum longevity') |

## Cetorhinus maximus (basking shark). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Cetorhinus_maximus/

| The page says | The source says |
| :--- | :--- |
| They migrate mostly according to how much plankton there is. | Basking sharks migrate mostly based on the abundance of plankton. |

## Rigby et al. (2021). Cetorhinus maximus. The IUCN Red List of Threatened Species 2021: e.T4292A194720078.

https://doi.org/10.2305/iucn.uk.2021-1.rlts.t4292a194720078.en

| The page says | The source says |
| :--- | :--- |
| The IUCN Red List rates it Endangered. | IUCN Red List category: Endangered (EN). |

## Gore et al. (2008). Transatlantic migration and deep mid-ocean diving by basking shark. Biology Letters.

https://doi.org/10.1098/rsbl.2008.0147

| The page says | The source says |
| :--- | :--- |
| Scientists had assumed that basking sharks lived in separate populations. | basking sharks (Cetorhinus maximus) have been assumed to remain in discrete populations |
| Then a 2008 study followed a shark tagged off the British Isles. She travelled 9,589 kilometers while crossing the North Atlantic, and her tag came off near Newfoundland, Canada. | results on the tracks and behaviour of two basking sharks tagged off the British Isles, one of which released its tag off Newfoundland, Canada. During the shark's transit of the North Atlantic, she travelled a horizontal distance of 9589 km (note: 2008 is the paper's year) |
| It was the first evidence of a link between European and American populations. | This result provides the first evidence for a link between European and American populations |
| She also reached 1,264 meters deep, a record at the time, which indicated that the species uses deep water beyond the edge of the continental shelf | reached a record depth of 1264 m. This result provides the first evidence for a link between European and American populations and indicates that basking sharks make use of deep-water habitats beyond the shelf edge (note: 'a record at the time': the 2008 paper's record, not checked against later tagging) |
| travelled 9,589 kilometers across the North Atlantic and reached 1,264 meters deep, a record in 2008. | During the shark's transit of the North Atlantic, she travelled a horizontal distance of 9589 km and reached a record depth of 1264 m. (note: blockquote restates the body figures; 2008 is the paper's year) |
| In a 2008 study, one shark tagged off the British Isles reached 1,264 meters deep while crossing the North Atlantic, a record at the time. The result indicated that the species uses deep water beyond the edge of the continental shelf. | two basking sharks tagged off the British Isles ... During the shark's transit of the North Atlantic, she travelled a horizontal distance of 9589 km and reached a record depth of 1264 m. This result provides the first evidence for a link between European and American populations and indicates that basking sharks make use of deep-water habitats beyond the shelf edge (note: 2008 is the paper's year; 'a record at the time' dates the abstract's 'record depth') |

## Skomal et al. (2009). Transequatorial Migrations by Basking Sharks in the Western Atlantic Ocean. Current Biology.

https://doi.org/10.1016/j.cub.2009.04.019

| The page says | The source says |
| :--- | :--- |
| Sharks tagged off southern New England have been tracked to the Bahamas, the Caribbean Sea and on into the Southern Hemisphere. In those waters they descended to the mesopelagic, or twilight, zone, and some stayed there for weeks to months at a time. | Tagged sharks moved from temperate feeding areas off the coast of southern New England to the Bahamas, the Caribbean Sea, and onward to the coast of South America and into the Southern Hemisphere. When in these areas, basking sharks descended to mesopelagic depths and in some cases remained there for weeks to months at a time. (note: 'twilight zone' is the common name of the mesopelagic) |

## Sims (2000). Filter-feeding and cruising swimming speeds of basking sharks compared with optimal models: they filter-feed slower than predicted for their size. Journal of Experimental Marine Biology and Ecology.

https://doi.org/10.1016/s0022-0981(00)00183-0

| The page says | The source says |
| :--- | :--- |
| In one study that tracked six basking sharks at the surface | Movements of six basking sharks (4.0-6.5 m total body length, L(T)) swimming at the surface were tracked |
| they swam about 24% slower while filter-feeding than while cruising with their mouths closed | swimming speeds during filter-feeding were significantly lower than when cruise swimming with the mouth closed, indicating basking sharks select speeds approximately 24% lower when engaged in filter-feeding |
| possibly to avoid the energy cost of extra drag at faster feeding speeds | This reduction in speed during filter-feeding could be a behavioural response to avoid increased drag-induced energy costs associated with feeding at higher speeds. |
| a shark that swims about 24% slower while filter-feeding than while cruising with its mouth closed | swimming speeds during filter-feeding were significantly lower than when cruise swimming with the mouth closed, indicating basking sharks select speeds approximately 24% lower when engaged in filter-feeding (note: Settle #387: vibe.reason mechanism replaces 'epic slow-motion oceanic migrations'.) |