Mimic Octopus(Thaumoctopus mimicus)

                       The Mimic Octopus

                         “King of Mimicry”

Kingdom: Animalia

Phylum : Mollusca

Class :Cephalopoda

Order : Octopoda

Family : Octopodidae

Sub family : Octopodinae

Genus : Thaumoctopus

Species : T. mimicus

 Author :  Norman & Hochberg, 2005

The term mimic refers to imitate or impersonate of voice and action of others. Thaumoctopus mimicus, is an octopus that mimics other marine organisms. The distribution is restricted to Indo-Malay archipelago; it was first explored at off coast of Sulawesi in Indonesia on 1998. The average size of Mimic Octopus is 60 cm and their arms can extend up to 25 cm. Mimic Octopus is characterized by brown color with white strips. Like other octopus it has 8 arms with 2 rows of suckers and a mantle containing 3 hearts. The suckers have touch sensors and chemo receptors, that helps them to sense and taste the food before eating.  These creatures prefer muddy bottom in the sea and moves over bottom by jet propulsion using siphon. It is the only known marine species that can impersonate several animals. Since, the body of octopi are made of nutritionally fleshy muscle; devoid of spines it makes them the most susceptible prey for predators such as sharks, damsels and barracuda. They mimic the marine animals basically for two reasons first, to escape from its predator and secondly to catch its prey by mimicking as a mate of its prey organism example, it mimics as mate of crab.  

Behaviour

These intelligent creatures can mimic like the following marine animals

Lion fish:Spreading its arms wide and keeping the head in horizontal position, imitates a poisonous lion fish.

 Flat fish: Pulling its all arm backward and moving forward imitates a poisonous striped flat fish.

Sting ray: Moving forward by Pulling its all arm backward with one arm left behind impersonates sting ray with its deadly tail.

 Sea snakes: burrowing in sediment by leaving 2 arms outside the sediment bottom mimics banded sea snake.

 Jelly fish: It puffs its head and siphon to imitate deadly jelly fish, then it moves to the surface and sinks down like jelly fish.

Acknowledgement 

The pictures were collected from following links

http://www.townsvillebulletin.com.au/article/2013/03/16/377473_news.html

http://pensivetoaster.com/2013/05/08/real-life-shape-shifter/

http://dive.nl/images/mimic-octopus-1?size=2560*1600

http://science.howstuffworks.com/zoology/marine-life/octopus-camouflage1.htm

http://artsonearth.com/tag/mimic-octopus

Nudibranch (Glaucus atlanticus)

                           Blue Dragon of sea

Kingdom: Animalia

Phylum: Mollusca

Class: Gastropoda

Order: Nudibranchia

Family: Glaucidae

Super family: Aeolidioidea

Genus: Glaucus

Species :G. atlanticus

Author: (Forster, 1777)

The term Nudibranch is derived from two ancient words namely - Nudus (naked) in Latin and  brankia (gillsGreek). They are shelless mollusc belonging to order Nudibrachia . There are around 3000 species of nudibranchs are in the world. Glaucus atlanticus is one among them belonging to the family Galucidae  . They are commonly termed as sea swallows, blue dragon, blue sea slugs based on its floating capacity on pealgic water and appearance. Glaucus is the only genus with two species in the family Glaucidae .They live in pelagic waters and are distributed in both tropical and temperate regions all around the world . They  float upside down in the pelagic surface due to  the location of air sac  on the ventral side. Dorsal side of the mollusc is silvery white or grey colour and ventral side is dark blue which gives a counter shading property when the mollusc swims upside down. Average size of this mollusc varies from 35mm to 43 mm.  It has a blunt head, elongated  and tapered body with 3 pairs of appendages . Finger like projections rise from appendages called “cerata”. These creatures move in water by rowing the cerata in the appendages and moving their body up and down. Glaucus are hermaphroditic in nature (both male and female sex organs are present in the same animal). Egg strings are produced and each egg is 60-75 mm wide and 75-97 mm long. Within 48-60 hours trochophore larva is formed, followed by veliger with larval shell after 3 days. These shelless molluscs contain shells during their veliger stage and sheds it when it grows as adult.  Like other Nudibranchs, blue sea slugs are also carnivores feeding on a variety of pelagic organisms including the dangerous Portuguese Man O’ War, Physalia physalis; the ‘by-the-wind-sailor’Velella velella ; the blue button, Porpita porpita ; and the violet snail, Janthina janthina . One peculiar character of this tiny creature is separation of stinging cells (Nematocysts) of hydroids in digestive system after feeding. It stores the nematocysts in minute sac like structure called “cnidosacs” present in the tip of each cerata and uses for defence and predation. Since, it stores more nematocysts it can cause more damage than the hydroids.

Acknowledgements : 
Pictures were collected from following links

http://www.impactnews.ro/Green/FOTOGALERIE:-Dragonul-albastru.-Incredibila-creatur%C4%83-a-ad%C3%A2ncurilor-89274

http://www.taringa.net/posts/imagenes/15567295/Blue-Dragon.html

http://ferrebeekeeper.wordpress.com/2012/05/30/predators-of-the-open-ocean-sea-slugs/

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 .