Head to head
Whale Shark vs Basking Shark
The two biggest fish alive are both sharks, and both make their living straining tiny prey from the water rather than hunting. The whale shark is the larger, a warm-water species covered in a chessboard of pale spots. The basking shark is the second largest fish, a plainer grey shark of cooler seas. Swimming beside either one is completely safe.
| Whale Shark | Basking Shark | |
|---|---|---|
| Size rank | Largest fish in the world (12 m or more) | Second largest fish (up to about 10 m) |
| Water temperature | Warm tropical and subtropical seas | Cool temperate and boreal seas |
| Appearance | Dark with a grid of white spots and stripes | Plain grey-brown; huge gill slits nearly meeting on top |
| Feeding method | Active: can suction-feed and ram-feed | Passive: only ram-feeds with mouth held open |
| Diet | Fish eggs, krill, small fish, plankton | Zooplankton, mainly copepods |
| Winter behaviour | Continues feeding; makes long migrations and deep dives | May shed its gill rakers and move to deep water for months |
| Reproduction | Live birth; one female carried about 300 pups | Live birth; gestation possibly 2 to 3 years |
| Conservation status | Endangered | Endangered |
Whale Shark vs Basking Shark: common questions
How do you tell a whale shark from a basking shark?
Colour and location are the easiest cues. A whale shark is dark grey to brown with a bold, regular pattern of pale spots and lines, like a net thrown over it, and it lives in warm water. A basking shark is a uniform dull grey-brown with no spots, and it lives in cool water. Up close, the basking shark's gill slits are spectacularly long, running almost all the way around the neck and nearly meeting over the back, while a whale shark's gill slits are more modest. The whale shark's mouth is set right at the front of a very flat, wide head; the basking shark has a more pointed, cone-shaped snout with the mouth below it.
Are either of them dangerous to swimmers?
No. Both are filter feeders with tiny teeth that play no role in feeding, and neither has any interest in a person. Whale sharks are the target of a large tourism industry precisely because snorkellers can swim alongside them safely, and basking sharks will glide past divers without reacting. The only real hazards are practical: these are very large animals, and a careless swimmer can be struck by a tail or a fin, and boats can collide with a surface-feeding basking shark. Guidelines ask people not to touch either species or block its path.
Why does the basking shark disappear in winter?
For a long time it was a genuine mystery, with basking sharks vanishing from the surface of northern seas every autumn. Tracking studies have now shown that they do not hibernate but move, some heading to deeper offshore water and some travelling long distances, including across the equator. There is also evidence that they shed and regrow their gill rakers seasonally, which would leave them unable to feed for a period. The likely picture is that when the plankton at the surface thins out in winter, basking sharks follow food into deeper water and become much harder to see.