Archer fish(Toxotes jaculatrix)

                     Under Water Archer 

Kingdom: Animalia

Phylum: Chordata

Class: Actinopterygii

Order: Perciformes

Family: Toxotidae

Genus: Toxotes

Species: jaculatrix

Author: Cuvier, 1816

Fishes forage for food in various ways and the way it forages it depends on the environment, physiology, morphology. Here, there is a fish that uses water as arrow to catch its prey. Archer fish is distributed in estuaries, mangrove swamps and river mouths of Indo-pacific waters. It posses laterally compressed body with five black markings on either sides. Unlike other fishes the dorsal fins present at the posterior end of the body. Juveniles grow in fresh water and move to brackish and then to sea when as it become adult. Mouth is protractible with groove in upper end that helps in ejecting water to catch its prey. This fish can grow up to 30 cm in length. Archer fish feeds on land based insects such as spider, grasshopper, butter fly etc.

Speciality of Predation
Every fish has their own way of predating their prey; Archer also follows its own way for predation. It spits water as arrow to catch the prey present above the surface of water. Strategy behind this is, when it sees the prey it roles its eye to get a full image of the prey on ventral temporal periphery of retina and spits the water by placing tongue at groove present in upper end of mouth. It acts as a tube through which the water passes in jet speed by compressing operculum. It usually shoots at an angle of 74 degree but, the aim is accurate at 45 and 110 degree. Accuracy is not only because of having good eyesight, it also knows to compensate refraction of light that passes air sea interface during aiming. Italian scientists demonstrated the force of the water is based on water dynamics rather than using internal muscles. It modulates the velocity of the jet as it alters its shape through air. The top of the jet increases in volume as it gets liquid from tail to form a big drop that hits insects with greater force.  Adults almost hit the prey in a single shot but, juveniles’ accuracy increases as it gets adult. Hence, juveniles hunt in groups to catch their prey.

Acknowledgement

Pictures and video were collected from following links

http://ies.franciscoasorey.ccmc.climantica.org/2012/10/28/un-chorro-mortal/

http://www.arastiralim.net/ilk/tag/hayvanlar-alemi/page/114

http://en.wikipedia.org/wiki/Banded_archerfish

http://www.free-pet-wallpapers.com/Aquarium-fish-pet-wallpapers/Freshwater-fish/Arcer-fish-banded-archerfish-(Toxotes-jaculatrix).html

http://www.youtube.com/watch?v=f8oV4RBYR9U

Oil Pollution Awareness week

                                              Oil pollution

BP accident 2010

There is variety of pollution's in oceans; oil pollution is one major among them. Some of the disaster such as “Exxon Valdez” incident in Prince William Sound, Alaska, 1993, braer, Off the Shetland Islands, 2010 BP leak in the Gulf of Mexico made people concern and aware about oil pollution. The pollutant is crude oil; oil pollution is caused due to accidents of oil tankers, explosion in offshore oil production rigs. The oil spills brings undesirable changes in water quality and marine flora & fauna.

           The oil mixes with water to form a substance called “mousse” which sticks on feathers of coastal birds and furs of marine mammals such as pinnipeds.  Feathers and furs are filled with air spaces to help in maintaining the body temperature by insulation. These oil spills fills the gap, make no way for the air spaces to insulate the body. Hence, coastal birds and marine mammals (Pinnipeds) die as a result of “hypothermia”. Oil slicks are also carried away to sandy & rocky shore by the tides and the waves. The grazers and filter feeders of these environments are affected heavily due to oil pollution.

Organ damage of marine fauna

  

Oil spills damage the eyesight of the marine animals and blind them .Hence, chance of being prey for predators is high.  Uptake of oil spills by marine organisms damages the internal organ such as lungs, kidneys, digestive tract by formation of ulcer, diseases etc. Marine mammals such as dolphins, whales frequently comes to surface for breathing using blowholes. Oil spills sticks to the blowholes of these animals and blocks the way for breathing, it leads to mortality. Oil spills also affect normal food chain of ocean by affecting primary producers such as phytoplankton and zooplanktons. All the above factors have ability to bring the name of the animal in endangered list for some period. After, destroying the surface or necktonic animals the oil seeps down to the bottom and also affects the benthic fauna such as crabs, shrimps on the sea floor.

  

Impacts on marine flora

Mangroves are sensitive to oil spills. Oil slicks carried out by tides and waves to mangrove environment coats the roots such as aerial root (pneumatophores) of mangroves such as Avicennia. It affects the oxygen exchange and salt excretion process of such mangrove. Lighter oil slicks are more penetrable than the heavier oil slicks into mangrove forest. Sea water soluble fraction (SWSF) of oil is a kind of dissolved or suspended tiny spills of oils. Toxic bits from this SWSF passes through the blades of sea grass and accumulates on chloroplasts interrupts the photosynthesis activity.

Acknowledgement : Pictures were collected from following links

http://econews.com.au/news-to-sustain-our-world/mexico-gulf-oil-spill-costs-transocean-1-4bn/

http://oils.gpa.unep.org/facts/wildlife.htm

http://www.marinemammalcenter.org/what-we-do/rescue/oil-spill-response.html

http://www.desdemonadespair.net/2012/10/us-downplayed-effect-of-deepwater.html

http://mariaabaca.com/bp-oil-spill-stil-having-effects-on-marine-life/

http://coastalcleanup.wordpress.com/category/mangrove/page/2/

Saw Fish (Pristis microdon)

                        SAW FISH(Pristis microdon)  

Kingdom:Animalia

Phylum:Chordata

Class:Chondrichthyes

Subclass:Elasmobranchii

Order:Pristiformes

Family:Pristidae

Genus:Pristis

Species:P.microdon

Author:Latham 1794

 The fish is known for its long saw like snout, high value fin and meat. They are most critically endangered species of shark belonging to the family Pristidae. Saw fishes are distributed in tropical areas of Indo-West Pacific region. Since, it has saw like snout it is commonly called as large tooth saw fish. It is characterized by long tapering snout with 14-22 large teeth on both sides. Space between last teeth is twice less than space between first teeth. Average size of these sharks is 5meters and it weighs about 600kg. The dorsal side of the fish is greenish grey or golden brown and creamy white in the ventral side. The pectoral fins are high and angular whereas dorsal fin is located in front of pelvic fin. They live in shallow water region with sandy or muddy bottom. Adults are found in seas and estuaries, but the juveniles are found in the rivers. The long snout with sharp teeth is a deadly weapon used for attacking the prey and also for self defence. Like most sharks it is also ovoviviparous, where the young ones develop inside the female body.

Feeding mechanism

Most of the elasmobranches with elongated snout don’t use their snout for sensing and capturing their prey. But Pristis microdon uses its snout to sense the electric fields of the prey and catches its prey. It uses its three sensory modalities (Vision, electron reception, mechanoreception) for feeding. The snout of pristid saw fish is compared with extinct sclerorhynchids saw fish. The extinct sclerorhynchids saw fish has functional teeth and dormant replacement teeth and P. Microdon’s saw consist of lateral teeth formed from baseline and lengthen snout with slimmer construction. This adaptation helps them to enter into a school of fish and swipe its saw laterally to injure the fishes. It easily catches those injured fishes which is separated from their school and feeds on them. It also uses it saw to cut the whales and sieve the sandy substratum to capture the buried prey. The dense distribution of photoreceptors shows several peaks mediating acute vision in Pristis microdon. Electron reception of pristids is higher than the rhinobatids shovel nose rays. Ampullae of lorenzini pores are present more in number, which helps to locate the prey easily.

Threats

Goa, India

Used as religious symbol at Taiwan temples 

All species of this shark are listed as “critically endangered” in IUCN(International Union for Conservation of Nature) red list. The reason for dwindling of the shark population is due to; increasing fishing activity as a result of high economic value of fin and meat. Since, all the species have elongated snout they get easily entangled in the fishing nets. They are highly susceptible to gill nets and have all possibilities of getting entangled. According to the report of discovery news (Discovery’s shark week Aug 4-10) these sharks are routinely killed and their meats are sold in the market. Sadly, the snout is also taken as a souvenir for display. In India it is protected under the wild life protection act.

Acknowledgement : Pictures were collected from following links 

http://sharkyear.com/2011/big-sawfish-caught-in-bay-of-bengal.html

http://www.cites4sharks.org/species/conservation-and-cites-s/

http://www.flmnh.ufl.edu/fish/Gallery/Descript/Freshwatersawfish/Freshwatersawfish.htm

http://www.dutchsharksociety.org/all-sawfish-species-are-near-extinct-so-if-you-see-one-report-it/

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 .