World’s largest species of fish has to survive longs periods of starvation despite weighing as much as THREE African elephants
- The dietary habits of whale sharks were examined by scientists at an aquarium
- Wild whale sharks hadn’t eaten in ‘weeks or months’ according to the experts
- The team also found that the animals ate more plants than previously thought
- The creatures may not have encountered food or may not eat while migrating
The largest fish on the planet survive long periods of starvation even though they weigh as much as three African elephants.
Despite their conspicuous size, many details of whale sharks’ lives in the open ocean remain a mystery even now – 183 years after they were first discovered.
Whale sharks can grow up to 39 feet long (12 metres) and weigh up to 46,297 lbs (21 metric tonnes).
Researchers compared blood tests from captive whale sharks living in an aquarium and samples from wild whale sharks who were accidentally entangled in fishing nets.
This made it possible to establish their dietary habits to gain a better picture of how often the ocean dwellers’ fed.
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The largest fish on the planet survive long periods of starvation. Despite their conspicuous size, many details of whale sharks’ lives in the open ocean remain a mystery, even 183 years after they were first discovered
Ocean scientists from the University of Tokyo in Japan carefully monitored the growth, diet, and health of the three whale sharks living in an aquarium.
After taking samples from the wild whale sharks they found that they had not eaten for weeks or months, according to the results.
‘Maybe they didn’t encounter any food, or maybe they just do not eat while migrating long distances,’ said Dr Alex Wyatt, a project researcher at the Atmosphere and Ocean Research Institute, who led the research.
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Whale sharks are officially listed as ‘endangered and are filter-feeding, soft-bodied fish that travel tropical oceans in search of their microscopic food.
Traditionally, researchers tracked their diets by taking body tissue samples and analysing the different forms, or isotopes, of carbon and nitrogen inside them.
But they found that they could not correctly interpret tissue isotope levels – which enter the creatures through their food and vary depending on where prey live – if they didn’t know each whale shark’s history of growth and diet.
They took about two teaspoons of blood from one of the whale shark’s pectoral fins.
Researchers combined blood tests from whale sharks living in an aquarium and samples from wild whale sharks who were accidentally entangled in fishing nets. This made it possible to establish their dietary habits to gain a better picture of the ocean dwellers’ eating habits
Ocean scientists from the University of Tokyo in Japan carefully monitored the growth, diet, and health of the three whale sharks living in an aquarium. After taking samples from the wild whale sharks they found that they had not eaten for weeks or months (stock image)
Dr Wyatt said: ‘Similar to blood tests performed when you visit the doctor, we are able to assess our health based on the contents of their blood.
‘We combine blood tests and tissue isotope analyses to create an accurate health check for the animals.’
The team also found that the wild whale sharks tested showed signs of eating significant amounts of plants and algae.
‘This is a somewhat surprising and controversial finding, since whale sharks are generally assumed to feed strictly on higher levels of the food chain,’ Dr Wyatt said.
Whale sharks at coastal sites had been seen eating a range of prey, from tiny krill and fish eggs up to small fish and squid.
The findings were published in the journal Ecological Monographs.
What are the 50 types of sharks and rays that are now facing extinction?
1 – Largetooth sawfish
2 – Green sawfish
3 – Smalltooth sawfish
4 – Narrow sawfish
5 – Angelshark
6 – Sawback angelshark
7 – Dwarf swfish
8 – Brazilian guitarfish
9 – Longhead eagle ray
10 – Ornate eagle ray
11 – Ornate sleeper ray
12 – Caribbean electric ray
13 – Smoothback angel shark
14 – Mottled eagle ray
15 – Natal shyshark
16 – Winghead shark
17 – Whale shark
18 – Zebra shark
19 – Sand tiger shark
20 – Bigeye thresher shark
21 – Bowmouth guitarfish
22 – Great hammerhead
23 – Basking shark
24 – Bluegray crpetshark
25 – White skate
26 – Snaggletooth shark
27 – Daisy stingray
28 – Blackchin guitarfish
29 – Scalloped hammerhead
30 – Shortnose guitarfish
31 – Roughnose stingray
32 – Sharpfin houndshark
33 – Harrisson’s dogfish
34 – Fanray
35 – Whitespotted izak
36 – Honeycomb izak
37 – Spotback skate
38 – Common guitarfish
39 – Great white shark
40 – Longnose marbled whipray
41 – White-edge whipray
42 – African wedgefish
43 – Giant freshwater whipray
44 – Kitefin shark
45 – Tope shark
46 – Porbeagle
47 – Longfin mako
48 – Shortfin mako
49 – Spotted shovelnose ray
50 – Pelagic thresher
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