Ocean’s largest inhabitants under the radar…until now

In the past few weeks, two great findings have surfaced from recent ocean research. Two giant species – a shark and a whale – are giving up surprising secrets about their lives. CI’s Bryan Wallace reports:

Multitudes of animal species continue to evade detection by science, mainly because they are really hard to find. Many are tiny, or well-hidden, or live in places that people have a hard time getting to (or escaping from). While roughly a couple of million species have been officially catalogued, perhaps tens (hundreds?) of millions of species remain undiscovered.

So you would figure that we know just about all there is to know about the planet’s biggest species – the ones that rival monster trucks and ocean liners in size…but you’d be wrong. In fact, scientists are still uncovering secrets as to the whereabouts and wanderings of two of the largest animals that have ever lived.

Basking Shark (Cetorhinus maximus)
© Alan James/Minden Pictures

The basking shark (Cetorhinus maximus) is the world’s second largest fish; only the appropriately named whale shark (Rhincodon typus) is larger.

Basking sharks can reach lengths of 10-12 meters (33-40 feet), and are known for swimming with their cavernous mouths – big enough to swallow a person whole (theoretically speaking) – wide open to take in and sieve tiny plankton from the water.

They inhabit mostly temperate (higher-latitude) waters around the world where oceanographic conditions are right for feeding, but they seem to disappear from these areas in the winter.

Where do they go? Do they hibernate? Do they ‘fly south’ like migratory birds and elderly Americans from northern states?

To solve this mystery, marine biologists from Massachusetts and Maine deployed sophisticated satellite-linked archival tags on two dozen basking sharks from off the coast of Cape Cod. To the scientists’ surprise, the sharks crossed 2000 km (more than 1,200 miles) of ocean to previously unknown locations throughout the sub-tropical and tropical western Atlantic. This is also the first ever use of this type of technology to record a fish species crossing the equator.

This expanded knowledge of basking shark geographic range shines new light on many aspects of this species’ biology, particularly reproduction, but also demonstrates the importance of tropical as well as temperate waters to these far-ranging behemoths.

Check back later this week for Part 2 of Bryan’s consideration of these colossal ocean mysteries…

Comments

  1. Pingback: Ocean’s largest inhabitants under the radar…until now, Part 2 | Conservation International Blog

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