A whale shark is the worlds biggest species of fish and you have the opportunity to snorkel with them. Every year from April to July the whale sharks come to Ningaloo Reef at Coral Bay.
A whale shark can grow up to 15m long and as they are filter feeders they are harmless to humans. They cruise the world's oceans looking for large concentrations to feed on. Ningaloo Reef is one of the few places in the world they appear regularly in large numbers.
This is an opportunity in a life time and people travel all over the world to the Ningaloo Reef during this time to see and swim with them. You will need to be a confident swimmer.
INTERESTING INFO ABOUT THE WHALE SHARK
It is rare to see a whale shark swimming alone. Smaller fish like to swim with whale sharks - sometimes even a whole school of fish will be swimming around them. Pilot fish swim around their head. A popular theory for this is for protection. With the size of the whale shark, the enemy of the pilot fish are too scared to come close therefore leaving the pilot fish alone. Remoras also swim with them. The remoras use its sucker to attach itself to the whale shark and helps the whale shark by eating parasites off its skin.
Whale sharks are considered to be good-luck fish.
The Japanese fishermen are careful not to catch a whale shark. They call them "ebisuzame" which is a good luck symbol.
In Vietnam they are called "Ca Ong", which means "Sir Fish". Sir Fish is a God the Vietnamese fishermen pray to for protection and good catches of fish.
WHALE SHARK BODY PARTS
The first of the whale shark body parts is its teeth. They have thousands of tiny teeth inside its mouth - sometimes up to 4,000. These teeth are about the size of the tip of a match-stick. For the figures people that is about 0.3cm or an 1/8 of an inch.
The teeth are arranged in the mouth in 300 rows. Obviously these teeth are not big enough to be used to eat but they are big enough to help them catch and eat. In fact it is a bit of a mystery why they even have teeth. The teeth are similar to what you will find on a file or rasp.
With all of these teeth another important body part is its mouth. It has a huge mouth which can be up to 2 metres wide. The mouth is at the very front of its head (not on the underside of the head like in most sharks). The head needs to be big to accommodate this huge mouth. It has a wide, flat head, a rounded snout and small eyes. Other body parts include 5 very large gill slits, 2 dorsal fins (on its back) and 2 pectoral fins (on its sides). The first dorsal fin is much larger than the second dorsal fin, and set rearward on the body. Its tail has a top fin much larger than the lower fin. These are called lobed caudal fins and are semi-lunate in adults.
Whale sharks catch their food (plankton and small fish and squid), by swimming with their mouth open. As they swim, water and small animals go into their mouth. The water leaves through its gill slits, trapping food in the gill rakers.
Whale sharks have five gill slits on each side of their head. Gill rakers strain the good stuff out of all this water they take into their mouth and use the good parts for food.
Whale sharks breathe with gills. Gills are used to get oxygen from the water and this helps them breathe.
WHALE SHARK REPRODUCTION AND BIRTH
It was widely believed the whale shark reproduction process and birth was like other fish (oviparous - egg cases expelled from the female's body and hatched on the sea floor). This would involve a female whale shark laying her eggs and the male fertilising them. We now know that a female keeps her eggs inside her body until the babies are ready to be born (viviparous - egg cases hatching in the mother's uteri, with the female giving birth to live young).
A whale shark may have hundreds of thousands of eggs inside her but not every egg will become an embryo. Some of these eggs are actually food for the other eggs that do develop into embryos. An embryo eats the other eggs for energy and therefore to grow.
In 1995 a team of scientists found an 11 metre female whale shark in Taiwan that had been killed by a fisherman. There were about 300 embryos inside her ranging in length from 42 to 63cm. Amazingly, 15 of the embryos were still alive and were ready to be born - an extremely rare form of birth. The egg capsules were amber in colour, with a smooth texture and had a respiratory opening on each side. There were an equal number of male and female babies.
The whale sharks that are born are called pups - the pups are over 60cm (2 feet) long.
Sexual maturity does not occur until they reach about 9metres long. This means a whale shark reproduction maturity age of about 30 years old. Whale sharks live for about 60-100 years.
INTERESTING FACTS ABOUT WHALE SHARKS
They are actually fish and not whales. Not only that but they are the biggest fish in the world and once fully grown they can be as long as 15 metres in length and weigh 20 tonnes.
They are the biggest fish in the world but they are also a very gentle fish. They eat only plankton and other small fish and are not interested in eating other things. That is why people from all over the world travel to Ningaloo Reef at Coral Bay during the spawning of the coral to swim with them. The spawning of the coral happens between March and June. This attracts the whale shark for food.
The correct species name of a whale shark is Rhincodon typus with "Rhincodon" meaning "rasp teeth" - which is what the whale sharks 4,000 tiny teeth look like (a rasp).
Whale shark are a pelagic species. This means they swim in the open ocean but usually found in the tropical parts of the oceans.
They are reddish brown in colour with a pattern of lines that crisscross each other on their skin. Inside these grids are yellow dots.
Additional interesting facts about whale shark is they pay no attention to boats. At their size why would they? So boat owners and captains need to be careful where whale sharks are and it is up to the boat to avoid "accidents".
No comments:
Post a Comment