Holothuria leucospilota

                                   Holothuria leucospilota

                                                                  Kingdom: Animalia

                                                                  Phylum: Echinodermata

                                                                  Class: Holothuroidea

                                                                  Order: Aspirochirotida

                                                                  Family:Holothuriidae

                                                                  Genus : Holothuria

                                                                  Species: leucospilota

                                                                 Author: Brandt, 1835

Tentacles with bush like branchinges  

Photographed at Manadhoo,
Noonu Atoll, Maldives 

Sea cucumbers are echinoderms, a group of spiny skinned marine organisms which includes also sea stars and sea urchins. They are known for their leathery skin, elongated cucumber shape body and the fact that they are eaten as delicacy in some Asian countries. For this last reason, they are heavily poached in many countries, and some species are in danger of extinction. Black long sea cucumber is one among them known for its black colour with long stretchable body. It is characterized by charcoal black colour with soft cylindrical body covered with soft papillae. The length ranges from 30 -40 centimetres when it is relaxed; but, biggest specimens can stretch their body up to 60 centimeters. The posterior end of the cucumber is tapered and anterior end possesses 20 branching tentacles with surrounding the mouth. H. leucospilota is one of the common species that is distributed throughout the Indo pacific, Central America, east coast of Africa, Red Sea and north east coast of Australia. Like most holothurians, they are scavengers that collect the sand and separates bio film and organic matter; they feed on diatoms, bacteria and microalgae.  It is a shallow water cucumber found in rocky shore and coral reef areas distributed within 5 meters and maximum up to 20 meters depth. According to IUCN it is one of the most abundant species of sea cucumber with to H.atra.
 

Cuvierian tubules

There are clusters of tubules located at the base of respiratory tube that lie freely in the coelomic fluid in the body cavity named Cuvierian tubules. There may be lot of questions for readers on why it is named Cuvierian and what these tubules are. It’s because it is named after the French 19th century zoologist Georges Cuvier who described it first. These are sticky tubules that are released by a sea cucumber to avoid the predator when it gets threatened.  When the sea cucumber gets stressed it contracts its body causing cloacal wall to tear and release of tubules through anus. As soon as the thread reaches the sea water it extends due to forcing of water from respiratory tree of sea cucumber and becomes more adhesive. The tubules have the capacity of expanding 20 times of their actual length. Like lizards tail, the tubules can be regenerated and regeneration time varies from one species to another in case of H.leucopilota it takes 15-17  days to regenerate the tubules

Human vs H.leucospiloata

H.leucospilota is consumed in Fiji, Solomon Islands, Tonga, Cook Islands, Guam and Marshall Islands. Though, this species widely consumed in western pacific region, it doesn’t fetch high commercial value. This species proved to be surviving in wide range of temperature, salinity and other physiochemical factors that makes high volume of its population. So far, the population is listed in least concern in IUCN red list, but there is high possibility for exploitation of this species since the population of higher commercial value species is getting depleted. 

Acknowledgement 

Information where collected from the following references

http://species-identification.org/species.php?species_group=nasc&menuentry=soorten&id=65&tab=beschrijving

http://www.iucnredlist.org/details/180375/0

Gambierdiscus toxicus

                   Ciguatera Dinoflagellate

                    (Gambierdiscus toxicus)

                                  

                       

                  Domain: Eukaryota

                             Kingdom: chromalveolata

                             Phylum: Dinoflagellata

                             Class: Dinophyceae

                             Order: Goyaulacales

                             Family: Goniodomataceae

                             Genus: Gambeirdiscus

                             Species: G.toxicus

                             Author: Adachi and Fukuyo, 1979

Gambierdiscus toxicus is an armoured marine benthic and toxic dinoflagellate that is known for affecting tropical reef ecosystem. It was first discovered in Gambier Islands of French Polynesia and since this toxin producing dinoflagellate is in discoid shape it is termed as Gambierdiscus toxicus. They are distributed in reef areas of Pacific and Indian Oceans especially in the tide pools and lagoons. G.toxicus is a photosynthetic cell with yellow to golden- brown chloroplasts. This cell varies from oval to ellipsoidal shape with crescent shape nucleus. The cell is anterio-posteriorly compressed with smooth surface and numerous dense pores. Cell length ranges from 24-60µm in length and 42-140 µm in transdiameter. They grow as epiphytes (Plant that grows on another plant) in macroalgae and dead corals. Each strain of G.toxicus prefers different algae example Hawaiian strain prefers red algae (Spyridia filamentosa). These microscopic cells reproduce asexually by binary fission. 

Controlling factors of G. toxicus distribution

Scanning electron microscopic picture of Gambierdiscus toxicus

The distribution of G.toxicus is restricted by the following factors. Water temperature that ranges from 25°C-29°C promotes the growth of G.toxicus. Macrophytes(Algae) and biofilms acts as good substrate for G.toxicus to attach. Water with low to moderate turbidity and stable salinity of 33 ppt creates a suitable condition for G.toxicus to multiply. It prefers only low light intensity for growth (Ten percent of incident ray is enough for this dinoflagellate to bloom) and it shades itself under substrate(Macro algae) in high light environment. All the above environmental factors also promote coral reef formation. The density of the G.toxicus is associated with physio-chemical parameters of coral reef ecosystem. Hence, both coral reef and G.toxicus overlaps, this yields a way for this toxic dinoflagellate to enter in the food chain of coral reef fishes. But, in some cases these cells also exist in macrophyte abundant area where the reef is completely absent (NE Coast of Australia).

G.toxicus vs human

They are known for producing toxins such as cigua toxin, maitotoxin and gambeir toxin that accumulates in the fish and transfers from one fish (Herbivores) to another (carnivores) through a process called bio magnification. It also changes the behavior and suppresses the immunity of fish that leads disease proliferation. It affects around 400 species of fish especially, fishes belonging to scombridae including high commercial value fishes such as Tuna and Seer fish. It causes ciguatera (Ciguatera Fish poisoning) to humans who consumed the affected fishes. Symptoms includes Nausea, vomiting, muscle pain, numbness, tingling and one of the peculiar symptoms of this disease is cold allodynia (cold Burning sensation). The people in contact with cold substance feel burning sensation. The toxin is odour less, tasteless and heat resistant; so it doesn't detoxify while cooking. 

Acknowledgement 
Pictures and information were collected from the following links 

http://eol.org/pages/899625/overview

http://research.myfwc.com/engine/download_redirection_process.asp?file=gambierdiscus_toxicus_2607.pdf&objid=24290&dltype=article

http://species-identification.org/species.php?species_group=dinoflagellates&id=59

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3182139/

http://gambierdiscuswiki.wikispaces.com/Ecology

http://www.utexas.edu/news/2012/02/15/ciguatera_fish_poisoning/

https://www.e-education.psu.edu/earth103/node/718

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/