Whale Shark (Rhincodon typus)

          Whale shark (Rhincodon typus ) Smith, 1828

                            Scientific classification

                                       Kingdom: Animalia

                                       Phylum: Chordata

                                       Class: Chondrichthyes

                                       Subclass: Elasmobranchii

                                       Order: Orectolobiformes

                                       Family: Rhincodontidae
                                       (J. P. Müller and Henle, 1839)

                                       Genus: Rhincodon (Smith, 1828)

                                       Species: R. typus

Whale sharks are the largest known living fish in the world distributed in tropical oceans and warm waters. Though it looks big , they are filter feeders feeds on plankton and sometimes it also feeds small fishes . Since, it feeds like baleen whale it obtained the name whale shark. They migrate across the oceans and migratory patterns are depends on locations productivity and breeding behaviour  Dorsal side of the fish is grey colour and ventral or belly is white in colour . It is a counter shading property possessed by all pelagic fishes , where as colour of the dorsal side match’s the ocean’s bottom and colour of ventral side match’s the colour of upper view from the bottom . Dorsal side as three longitudinal prominent ridges (carinae) and pale yellow colour spots .The upper lobe of juveniles’ caudal fin is longer than lower lobe (Heterocercal) and the caudal turns into semi lunate when it becomes adult. It has a terminal mouth which can measure up to 1.5 meters consisting 10 filter pads with 300 -350 tiny teeth in between to filter plankton . Whale sharks  possess 5 pairs of big gills internally modified into filters to trap prey while filtering water . The average size of whale sharks are 10 meters and maximum sized were measured up to 16 meters. with 34 metric tons of weight.Whale sharks are ovoviviparous  and female provides protection to the internally developing young one in egg and gives birth to live young ones. The hatched juvenile ranges from 0.4 meter-0.6 meter in length .It has a life span up to 70 years. 

Natural Threats

 The juveniles of whale sharks are attacked by killer whale and some larger sharks such as great white sharks.

      Whale sharks skin is covered by dermal denticles which makes the skin tough and this is natural mechanism for defence . It helps them to survive from attack by other predatory sharks .

Anthropogenic threats 

Anthropogenic activities have brought the whale sharks name in (Vulnerable) IUCN red list category. Whale sharks are consumed  for it’s meat as a delicacy and in countries such as Taiwan  and Pakistan. Poaching is one of the major anthropogenic activity for decline in whale shark populations. Entangling in fishing net and injury caused by propellers of boat are some of other man made threats to this under water giant .

Acknowledgements : Pictures were collected from Wikimedia , www.nationalgeographic.com , www.aboututila.com, www.dailymail.co.uk, pandiving.blogspot.in , www.howitworksdaily.com .