The whale sharks of Donsol
The whale shark (Rhincodon typus) is the largest shark en also largest fish who populates our oceans. He has an average length of 12 to 15m, but also some specimen of 18 to 20m are spotted. They can weight up to 15.000 kg. The whale shark is from above dark grey, fully covered with big white/light yellow spots and he has a white belly. The whale shark has at each side 5 gill-openings and 3 furrows which take up almost his whole body. A whale shark can get 100 till 150 years old. At about 30 years they are sexually mature, males are than about 6m and females 8m long. There is still not much known about their reproduction and where they give birth. For a long time people thought whale sharks laid eggs, as about 50 years ago a whale shark egg was found, 36cm big. More recently it became clear they are egg-viviparous, they hatch in their mothers body just before they are born. Newly born whale sharks have a length of 50-60cm. As all sharks, whale sharks don’t take care of their young ones. It is still not known, how many descendents a pregnant female gets. At one caught of a pregnant female it turned out she had 300 embryo’s at her uterus. But if they are set free at the same time, is until today not clear.
Walvishaai-7.jpgThe whale shark has a flat and broad head, his mouth you’ll find at the top of his head (not under its head, like the most sharks) and is just as broad as his head. Although the whale shark is an plankton eater, he has in his broad mouth (often bigger as 2m) 300 rows of minuscule teeth, about 3000 in total. If a tooth breaks off or falls out, a tooth of the following row takes its place. The small teeth are hardly used. They are degenerated to small rasp teeth. The whale shark thanks its original name to this, ‘rhineodon’ means rasp tooth and became Rhincodon typus. But also his skin is sharp, his skin is sowed with thousands of backwards pointed teeth, also called placoide scales. These minuscule ‘skinteeth’, forms a kind of coat of mail, to make the skin more resistant against injuries and attached parasites. When swimming, they create a extreme low current resistance, which make them very efficient swimmers. Their raw skin is about 10cm thick.
The whale shark mainly feeds himself with plankton, but he also can consume shoals of little fish and squid. They suck their ‘prey’ in, after which they filter efficiently the water away by their gill. They can process about 6000 liter of water per hour.
The whale shark appears in tropical and sub tropical oceans all over the world. But there are only a few places in the world where you can spot them in numbers at certain periods.
Walvishaai-4.jpgIn Donsol we snorkelled 2 days with about 15 whale sharks a day. A very impressive and unforgettable experience. Due to the large amount of plankton in the water, about 50 whale sharks visit daily the bay of Donsol in March and April. Since 10 years this bay has become a Marine Park and the former whale shark hunters became guides and spotters, trained to show tourists their ‘butanding’, the local name for whale shark. First you have to register yourself at the visitor centre, where they show you also an education instruction on video and then you’re put to sea, in small local boats, with a maximum of 6 tourists by boat. A little later, they called already whale shark, so we had to put fast our fins and dive mask on and we were dropped in the water, just 25m in front of him. At first you hardly see anything, the visibility is quite bad, just 5m and then all of a sudden, right in front of you appears a huge broad head, 2m wide, very impressive, you only can see its head. It looks like he is at a collision course, he swims just as you at the surface. But just before he reach you, he dives a little below and passes you, just half a meter below. You turn around to see him swim under you away a little longer, but within 30 seconds he was gone. The boat picks you up and a little later the following whale shark is spotted. Now you know as soon as you see his head, you turn around and swim with him, the second time we saw him for about a minute, but at the end of the morning we could swim with him for 5 to 10 minutes, but then you’re completely exhausted. A whale shark swims relatively slow, about 5 km per hour, but to keep up with him, requires a lot and then just for a little while. Sometimes we were lucky they slowed a little down. But the advantage of snorkelling is, you’ll be picked up, then you can catch breath and wait for the next whale shark. We saw little ones of 6m, but also several big ones at least 12m long.
Unfortunately it was difficult to film and to take pictures, due to the bad visibility you only could see a part of the whale shark, a complete view was not possible, those images are just hazy, but these pictures give still an idea of those beautiful animals.