1.
Tamil Nadu
–
Tamil Nadu is one of the 29 states of India. Its capital and largest city is Chennai, Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by the union territory of Puducherry and the South Indian states of Kerala, Karnataka, and Andhra Pradesh. The state shares a border with the nation of Sri Lanka. Tamil Nadu is the eleventh-largest state in India by area and the sixth-most populous, the state was ranked sixth among states in India according to the Human Development Index in 2011, with the second-largest state economy after Maharashtra. Tamil Nadu is the second largest state economy in India with ₹13,842 billion in gross domestic product after Maharashtra. Tamil Nadu was ranked as one of the top seven developed states in India based on a Multidimensional Development Index in a 2013 report published by the Reserve Bank of India and its official language is Tamil, which is one of the longest-surviving classical languages in the world. Tamil Nadu is home to natural resources. In addition, its people have developed and continue classical arts, classical music, historic buildings and religious sites include Hindu temples of Tamil architecture, hill stations, beach resorts, multi-religious pilgrimage sites, and eight UNESCO World Heritage Sites. Archaeological evidence points to this area being one of the longest continuous habitations in the Indian peninsula, the ASI archaeologists have proposed that the script used at that site is very rudimentary Tamil Brahmi. Adichanallur has been announced as a site for further excavation. About 60 per cent of the epigraphical inscriptions found by the ASI in India are from Tamil Nadu. A Neolithic stone celt with the Indus script on it was discovered at Sembian-Kandiyur near Mayiladuthurai in Tamil Nadu, according to epigraphist Iravatham Mahadevan, this was the first datable artefact bearing the Indus script to be found in Tamil Nadu. Mahadevan claimed that the find was evidence of the use of the Harappan language, the date of the celt was estimated at between 1500 BCE and 2000 BCE. The early history of the people and rulers of Tamil Nadu is a topic in Tamil literary sources known as Sangam literature, numismatic, archaeological and literary sources corroborate that the Sangam period lasted for about six centuries, from 300 BC to AD300. Three dynasties, namely the Chera, Chola and Pandya, ruled the area of present-day Tamil Nadu, the Chera ruled the whole of present-day Kerala and parts of western Tamil Nadu comprising Coimbatore, Dharmapuri, Karur, Salem and Erode districts from the capital of Vanchi Muthur. The Chola dynasty ruled the northern and central parts of Tamil Nadu from their capital, Uraiyur, All three dynasties had extensive trade relationships with Rome, Greece, Egypt, Ceylon, Phoenicia, Arabia, Mesopotamia and Persia. Trade flourished in commodities such as spices, ivory, pearls, beads, Chera traded extensively from Muziris on the west coast, Chola from Arikamedu and Puhar and Pandya through Korkai port. A Greco-Roman trade and travel document, the Periplus of the Erythraean Sea gives a description of the Tamil country, besides these three dynasties, the Sangam era Tamilakam was also divided into various provinces named nadu, meaning country
2.
India
–
India, officially the Republic of India, is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and it is bounded by the Indian Ocean on the south, the Arabian Sea on the southwest, and the Bay of Bengal on the southeast. It shares land borders with Pakistan to the west, China, Nepal, and Bhutan to the northeast, in the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives. Indias Andaman and Nicobar Islands share a border with Thailand. The Indian subcontinent was home to the urban Indus Valley Civilisation of the 3rd millennium BCE, in the following millennium, the oldest scriptures associated with Hinduism began to be composed. Social stratification, based on caste, emerged in the first millennium BCE, early political consolidations took place under the Maurya and Gupta empires, the later peninsular Middle Kingdoms influenced cultures as far as southeast Asia. In the medieval era, Judaism, Zoroastrianism, Christianity, and Islam arrived, much of the north fell to the Delhi sultanate, the south was united under the Vijayanagara Empire. The economy expanded in the 17th century in the Mughal empire, in the mid-18th century, the subcontinent came under British East India Company rule, and in the mid-19th under British crown rule. A nationalist movement emerged in the late 19th century, which later, under Mahatma Gandhi, was noted for nonviolent resistance, in 2015, the Indian economy was the worlds seventh largest by nominal GDP and third largest by purchasing power parity. Following market-based economic reforms in 1991, India became one of the major economies and is considered a newly industrialised country. However, it continues to face the challenges of poverty, corruption, malnutrition, a nuclear weapons state and regional power, it has the third largest standing army in the world and ranks sixth in military expenditure among nations. India is a constitutional republic governed under a parliamentary system. It is a pluralistic, multilingual and multi-ethnic society and is home to a diversity of wildlife in a variety of protected habitats. The name India is derived from Indus, which originates from the Old Persian word Hindu, the latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River. The ancient Greeks referred to the Indians as Indoi, which translates as The people of the Indus, the geographical term Bharat, which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. Scholars believe it to be named after the Vedic tribe of Bharatas in the second millennium B. C. E and it is also traditionally associated with the rule of the legendary emperor Bharata. Gaṇarājya is the Sanskrit/Hindi term for republic dating back to the ancient times, hindustan is a Persian name for India dating back to the 3rd century B. C. E. It was introduced into India by the Mughals and widely used since then and its meaning varied, referring to a region that encompassed northern India and Pakistan or India in its entirety
3.
Sri Lanka
–
Sri Lanka, officially the Democratic Socialist Republic of Sri Lanka, is an island country in South Asia near south-east India. Sri Lanka has maritime borders with India to the northwest and the Maldives to the southwest, Sri Lankas documented history spans 3,000 years, with evidence of pre-historic human settlements dating back to at least 125,000 years. Its geographic location and deep harbours made it of strategic importance from the time of the ancient Silk Road through to World War II. Sri Lanka was known from the beginning of British colonial rule until 1972 as Ceylon, Sri Lankas recent history has been marred by a thirty-year civil war which decisively ended when the Sri Lankan military defeated the Liberation Tigers of Tamil Eelam in 2009. A diverse and multicultural country, Sri Lanka is home to many religions, ethnic groups, in addition to the majority Sinhalese, it is home to large groups of Sri Lankan and Indian Tamils, Moors, Burghers, Malays, Kaffirs and the aboriginal Vedda. Sri Lanka has a rich Buddhist heritage, and the first known Buddhist writings of Sri Lanka, Sri Lanka is a republic and a unitary state governed by a semi-presidential system. The legislative capital, Sri Jayawardenepura Kotte, is a suburb of the capital and largest city. Along with the Maldives, Sri Lanka is one of the two countries in South Asia that are rated among high human development on the Human Development Index. In antiquity, Sri Lanka was known to travellers by a variety of names, according to the Mahavamsa, the legendary Prince Vijaya named the land Tambapanni, because his followers hands were reddened by the red soil of the area. In Hindu mythology, such as the Mahabharata, the island was referred to as Lankā, in Tamil, the island is referred to as Eelam. Ancient Greek geographers called it Taprobanā or Taprobanē from the word Tambapanni, as a British crown colony, the island was known as Ceylon, it achieved independence as the Dominion of Ceylon in 1948. The country is known in Sinhalese as Śrī Laṃkā and in Tamil as Ilaṅkai, in 1972, its formal name was changed to Free, Sovereign and Independent Republic of Sri Lanka. Later in 1978 it was changed to the Democratic Socialist Republic of Sri Lanka, as the name Ceylon still appears in the names of a number of organisations, the Sri Lankan government announced in 2011 a plan to rename all those over which it has authority. The pre-history of Sri Lanka goes back 125,000 years, the era spans the Palaeolithic, Mesolithic and early Iron Ages. Among the Paleolithic human settlements discovered in Sri Lanka, Pahiyangala and it is said that Kubera was overthrown by his demon stepbrother Ravana, the powerful emperor who built a mythical flying machine named Dandu Monara. The modern city of Wariyapola is described as Ravanas airport, early inhabitants of Sri Lanka were probably ancestors of the Vedda people, an indigenous people numbering approximately 2,500 living in modern-day Sri Lanka. According to the Mahāvamsa, a written in Pāḷi, the original inhabitants of Sri Lanka are the Yakshas and Nagas. Ancient cemeteries that were used before 600BC and other signs of advanced civilization has also discovered in Sri Lanka
4.
Adam's Bridge
–
Geological evidence suggests that this bridge is a former land connection between India and Sri Lanka. The bridge is 50 km long and separates the Gulf of Mannar from the Palk Strait, some of the sandbanks are dry and the sea in the area is very shallow, being only 1 to 10 metres deep in places, which hinders navigation. The bridge was first mentioned in the ancient Indian Sanskrit epic Ramayana of Valmiki, the Ramayana attributes the building of this bridge to Rama in verse 2-22-76, naming it as Setubandhanam, a name that persists until today. The sea separating India and Sri Lanka is called Sethusamudram meaning Sea of the Bridge, maps prepared by a Dutch cartographer in 1747, available at the Thanjavur Saraswathi Mahal Library show this area as Ramancoil, a colloquial form of the Tamil Raman Kovil. Another map of Mughal India prepared by J. Rennel in 1788 retrieved from the library called this area as the area of the Rama Temple. Many other maps in Schwartzbergs historical atlas and other such as travel texts by Marco Polo call this area by various names such as Sethubandha and Sethubandha Rameswaram. The western world first encountered it in works in the 9th century by Ibn Khordadbeh in his Book of Roads and Kingdoms. The earliest map that calls this area by the name Adams bridge was prepared by a British cartographer in 1804, Adams Bridge starts as a chain of shoals from the Dhanushkodi tip of Indias Pamban Island and ends at Sri Lankas Mannar Island. Pamban Island is semi-connected to the Indian mainland by 2 km long Pamban Bridge, Mannar Island is connected to mainland Sri Lanka by a causeway. The border between India and Sri Lanka is said to pass one of the shoals constituting one of the shortest land borders in the world. Adams bridge and neighbouring areas like Rameswaram, Dhanushkodi, Devipattinam, Pamban Island with its small port of Rameswaram is about 2 km from mainland India. The Pamban Bridge crossing the Pamban channel links Pamban Island with mainland India and it refers to both, a road bridge and a cantilever railway bridge. Small boats would go below the 2065 m long road bridge, the problem in navigation exists because big ships cannot travel in the shallow waters of the Pamban channel. Dredging in this channel would cost more than dredging a channel in the Rama Setu area, hence, in 2005, the Government of India approved a multi-million dollar Sethusamudram Shipping Canal Project that aims to create a ship channel across the Palk Bay cutting across Rama Setu. A ferry service linked Dhanushkodi in India with Talaimannar in Sri Lanka, the service was part of the Indo-Ceylon Railway service during the British Rule. One could buy a ticket from Chennai to Colombo, whereby people travelled by rail from Chennai to Pamban island, go by ferry to Talaimannar. In 1964, a completely destroyed Dhanushkodi, as a train was about to enter the station. The tracks and the pier were damaged along the shores of Palk Bay
5.
Thamirabarani River
–
The Thamirabarani River (Tamil, தாமிரபரணி is a perennial river that originates from the famous Agastyarkoodam peak of Pothigai hills of the Western Ghats, above Papanasam in the Ambasamudram taluk. It flows through Tirunelveli and Tuticorin districts of the Tamil Nadu state of southern India into the Gulf of Mannar and it was called the Tamraparni River in the pre-classical period, a name it lent to the island of Sri Lanka. The old Tamil name of the river is Porunai, from the source to sea, the river is about 185 kilometres long and is the only perennial river in South India. A meaning for the term following its derivation became copper-colored leaf, from the words Thamiram in Tamil/Sanskrit and parani meaning leaf/tree, other name derivations include the Pali term Tambapanni, Tamradvipa of Sanskrit speakers and Taprobana of ancient Greek cartographers. Its many name derivations of Tan Porunai include Tampraparani, Tamraparni, Tamiravaruni, Tan Porunai nathi finds mention by classical Tamil poets in ancient Sangam Tamil literature Purananuru. Recognised as a river in Sanskrit literature Puranas, Mahabharata and Ramayana. One important historical document on the river is the treatise Thamirabarani Mahathmiyam and it has many ancient temples along its banks. In the Mahābhārata the river is mentioned as Listen, O son of Kunti, in that asylum the gods had undergone penances impelled by the desire of obtaining salvation. The Thamirabarani River originates from the peak of the Pothigai hills on the slopes of the Western Ghats at an elevation of 1,725 metres above sea-level. The river is joined by its headwater tributaries Peyar, Ullar, Pambar before it flows into the Kariyar Dam reservoir, the river forms the Vaanatheertham waterfalls,40 metres high, as it enters the Kariyar reservoir. Servalar joins the Thamirabarani before it enters into the Papanasam lower reservoir, the river descends down the mountains near Papanasam, where it forms the Kalyanatheertham falls and Agasthiar falls. The river flows on the plains eastwards from Papanasam, the first tributary to join Thamirabarani in the plains is the Manimuthar River, which originating from Manjolai hills and joins Thamirabarani near Aladiyoor village. The towns Ambasamudram and Kallidaikurichi are located respectively on the left and right banks of Thamiraparani, the Gadananathi is fed by the Jambunathi and Ramanathi Rivers. The Pachaiyar River which originates from the Kalakkadu reserve forests at about 1,300 metres above sea level joins the Thamirabarani near Tharuvai village in Palayamkottai Taluk, the Chittar River runs almost parallel to Thamirabarani till it joins the main river near Sivalaperi. Thamirabarani passes through the taluks of Tirunelveli and Palayamkottai of Tirunelveli district and Srivaikundam, list of major tributaries The river drains into Gulf of Mannar near Punnaikayal in Tiruchendur taluk of Tuticorin district. The river drains with its tributaries an area of about 4,400 square kilometres, as most of its extensive catchment areas lie in the Western Ghats, the river enjoys the full benefit of both the monsoons, which make the river perennial. Since all its tributaries are arising from the Western ghats, the river is prone to heavy floods especially during the northeast monsoon and it flooded again in 2015 with water entering the Kurukuthurai Murugan Temple. It is fed by both the monsoons – the south west and the north-eastern and is seen in full spate twice a year if the monsoons do not fail
6.
South India
–
The region occupies 19. 31% of Indias land area. Covering the southern part of the peninsular Deccan Plateau, South India is bounded by the Bay of Bengal in the east, the Arabian Sea in the west, and the Indian Ocean in the south. The geography of the region is diverse, with two ranges, the Western and Eastern Ghats, bordering the plateau heartland. The Godavari River, Krishna River, Kaveri, Tungabhadra and Vaigai rivers are important non-perennial sources of water, Bangalore, Chennai, Hyderabad, Visakhapatnam, Vijayawada, Coimbatore and Kochi are the largest urban areas. Majority of the people in South India speak one of the four major Dravidian languages, Telugu, Tamil, Kannada and Malayalam. During its history, a number of kingdoms ruled over parts of South India whose invasions across southern and southeastern Asia impacted the history. Major dynasties that were established in South India include the Cheras, Cholas, Pandyas, Pallavas, Satavahanas, Chalukyas, Rashtrakutas, european countries entered India through Kerala and the region was colonised by Britain and other nations. HDI in the states is high and the economy has undergone growth at a faster rate than most northern states. Literacy rates in the states are higher than the national average with approximately 80% of the population capable of reading and writing. The fertility rate in South India is 1.9, the lowest of all regions in India, South India also known as Peninsular India has been known by several other names. Carnatic derived from Karnād or Karunād meaning high country has also associated with South India. Carbon dating on ash mounds associated with Neolithic cultures in South India date back to 8000 BCE, artefacts such as ground stone axes, and minor copper objects have been found in the region. Towards the beginning of 1000 BCE, iron technology spread through the region, however, the region was in the middle of a trade route that extended from Muziris to Arikamedu linking the Mediterranean and East Asia. Trade with Phoenicians, Romans, Greeks, Arabs, Syrians, Jews, the region was part of the ancient Silk Road connecting the Asian continent in the East and the West. C. to 14th century A. D. The Vijayanagara Empire, founded in 14th century A. D. was the last Indian dynasty that ruled over the region. The Europeans arrived in the 15th century and by the middle of the 18th century, the French, the British Empire took control of the region from the British East India Company in 1857. During the British colonial rule, the region was divided into the Madras Presidency, Hyderabad state, Mysore, Travancore, Kochi, Vizianagaram and a number of other minor princely states. After the independence of India in 1947, the region was organised into four states, Madras State, Mysore State, Hyderabad State and Travancore-Cochin
7.
Dugong
–
The dugong is a medium-sized marine mammal. It is one of four living species of the order Sirenia and it is the only living representative of the once-diverse family Dugongidae, its closest modern relative, Stellers sea cow, was hunted to extinction in the 18th century. The dugong is the strictly marine herbivorous mammal. The dugong is the only sirenian in its range, which spans the waters of some 40 countries and territories throughout the Indo-West Pacific, the northern waters of Australia between Shark Bay and Moreton Bay are believed to be the dugongs contemporary stronghold. Like all modern sirenians, the dugong has a body with no dorsal fin or hind limbs. The forelimbs or flippers are paddle-like, the dugong is easily distinguished from the manatees by its fluked, dolphin-like tail, but also possesses a unique skull and teeth. Its snout is sharply downturned, an adaptation for feeding in benthic seagrass communities, the molar teeth are simple and peg-like unlike the more elaborate molar dentition of manatees. The dugong has been hunted for thousands of years for its meat, traditional hunting still has great cultural significance in several countries in its modern range, particularly northern Australia and the Pacific Islands. The dugongs current distribution is fragmented, and many populations are believed to be close to extinction, the IUCN lists the dugong as a species vulnerable to extinction, while the Convention on International Trade in Endangered Species limits or bans the trade of derived products. Despite being legally protected in many countries, the causes of population decline remain anthropogenic and include fishing-related fatalities, habitat degradation. With its long lifespan of 70 years or more, and slow rate of reproduction, the word dugong derives from the Tagalog term dugong which was in turn adopted from the Malay duyung, both meaning lady of the sea. Other common local names include sea cow, sea pig and sea camel, Dugong dugon is the only extant species of the family Dugongidae, and one of only four extant species of the Sirenia order, the others forming the manatee family. It was first classified by Müller in 1776 as Trichechus dugon and it was later assigned as the type species of Dugong by Lacépède and further classified within its own family by Gray and subfamily by Simpson. Dugongs and other sirenians are not closely related to marine mammals. Dugongs and elephants share a group with hyraxes and the aardvark. The fossil record shows sirenians appearing in the Eocene, where they most likely lived in the Tethys Ocean, the Stellers sea cow became extinct in the 18th century. No fossils exist of other members of the Dugongidae, molecular studies have been made on dugong populations using mitochondrial DNA. The results have suggested that the population of Southeast Asia is distinct from the others, Australia has two distinct maternal lineages, one of which also contains the dugongs from Africa and Arabia
8.
Gulf of Mannar Marine National Park
–
The Gulf of Mannar Marine National Park is a protected area of India consisting of 21 small islands and adjacent coral reefs in the Gulf of Mannar in the Indian Ocean. It lies 1 to 10 km away from the east coast of Tamil Nadu and it is the core area of the Gulf of Mannar Biosphere Reserve which includes a 10 km buffer zone around the park, including the populated coastal area. The park has a diversity of plants and animals in its marine, intertidal. Public access inside the Park is limited to glass bottom boat rides, the 560 km2 park is part of the 140 km long and 25 km wide Mannar barrier reef. It lies between 8° 47’ to 9° 15’ N latitude and 78° 12’ to 79° 14’ E longitude, the 21 islands vary from 0.25 ha to 130 ha. Its surrounding shallow waters harbour three species of seagrass that are nowhere else in India. Representatives of every animal phylum known are found on this island, shingle,12.69 ha, elevation. 6m 9. 24174°N79. 23563°E /9.24174,79.23563. Tidal amplitude in the area is about. 5m, there were two more islands named Pandayan and Punnaiyadi at 8. 78075°N78. 19536°E /8.78075,78.19536 that were destroyed for construction of the new Tuticorn Port facilities. The park includes estuaries, mudflats, beaches and forests of the near shore environment and it also includes marine components such as coral reefs, seaweed communities, sea grasses, salt marshes and mangroves. Seaweed photo gallery Flora – Mangroves dominate the intertidal zones of the park islands and they consist of species belonging to the Rhizophora, Avicennia, Bruguiera, Ceriops and Lumnitzera genus. Introduced Prosopis genus of tree species are dominant on land in all the islands, pemphis acidula is the only endemic plant species. 12 species of sea grass and 147 species of seaweeds were recorded and this vegetation provides important feeding grounds for the vulnerable marine mammal, the Dugong, endangered Green turtles and Olive Ridley turtles. Sea grasses, photo gallery Fauna Vertebrates Dugong, a marine mammal is the flagship mammal of the park. It is an important habitat for the Cetaceans, Indo-Pacific bottlenose dolphin, Finless porpoise, Spinner dolphin, Common dolphin, Rissos dolphin, Melon-headed whale, and Dwarf sperm whale. Larger whales include Sperm whale, Minke whale, Brydes whale, Sei whale, and critically endangered species including Humpback whale, Fin whale, and Blue whale. About 510 of the 2,200 fin fish species in Indian waters are found in the Gulf, Coral associated ornamental fishes belonging to the family Chaetodontidae, Parrotfish, Amphiprion spp, Holocentrus spp, Scarus spp, Lutjanus spp and Abudefduf saxatilis are abundant. A unique endemic species of Balanoglossus – Ptychodera fluva, a fossil that links invertebrates and vertebrates, has been recorded only at Kurusadai. The coral fauna includes 106 species from 30 genus of hermatypes and 11 species from 10 genus of ahermatypes, including 13 new species, large areas of these reefs are in generally poor condition due to destructive human activities of the 150,000 persons living along the coast
9.
Coral
–
Corals are marine invertebrates in the class Anthozoa of phylum Cnidaria. They typically live in colonies of many identical individual polyps. The group includes the important reef builders that inhabit tropical oceans, a coral group is a colony of myriad genetically identical polyps. Each polyp is an animal typically only a few millimeters in diameter. A set of tentacles surround a central mouth opening, an exoskeleton is excreted near the base. Over many generations, the colony creates a large skeleton that is characteristic of the species. Individual heads grow by reproduction of polyps. Corals also breed sexually by spawning, polyps of the same species release gametes simultaneously over a period of one to several nights around a full moon and these are commonly known as zooxanthellae and the corals that contain them are zooxanthellate corals. Such corals require sunlight and grow in clear, shallow water, other corals do not rely on zooxanthellae and can live in much deeper water, with the cold-water genus Lophelia surviving as deep as 3,000 metres. Some have been found on the Darwin Mounds, north-west of Cape Wrath, Corals have also been found as far north as off the coast of Washington State and the Aleutian Islands. In his Scala Naturae, Aristotle classified corals as zoophyta, animals that had characteristics of plants and were therefore hypothetically in between animals and plants, the Persian polymath Al-Biruni classified sponges and corals as animals, arguing that they respond to touch. The phylogeny of Anthozoans is not clearly understood and a number of different models have been proposed, within the Hexacorallia, the sea anemones, coral anemones and stony corals may constitute a monophyletic grouping united by their eight-fold symmetry and cnidocyte trait. The Octocorallia appears to be monophyletic, and primitive members of this group may have been stolonate, the cladogram presented here comes from a 2014 study by Stampar et al. which was based on the divergence of mitochondrial DNA within the group and on nuclear markers. Corals are classified in the class Anthozoa of the phylum Cnidaria and they are divided into three subclasses, Hexacorallia, Octocorallia, and Ceriantharia. The Hexacorallia include the stony corals, the sea anemones and the zoanthids and these groups have polyps that generally have 6-fold symmetry. The Octocorallia include blue coral, soft corals, sea pens and these groups have polyps with 8-fold symmetry, each polyp having eight tentacles and eight mesenteries. Fire corals are not true corals, being in the order Anthomedusa of the class Hydrozoa, Corals are sessile animals in the class Anthozoa and differ from most other cnidarians in not having a medusa stage in their life cycle. The body unit of the animal is a polyp, most corals are colonial, the initial polyp budding to produce another and the colony gradually developing from this small start
10.
Sea turtle
–
Sea turtles, sometimes called marine turtles, are reptiles of the order Testudines. The seven extant species of sea turtles are, the green, loggerhead, Kemps ridley, olive ridley, hawksbill, flatback, the majority of a sea turtles body is protected by its shell. The turtles shell is divided two sections, carapace and plastron. The shell is made up of plates called scutes. The leatherback is the sea turtle that does not have a hard shell. Instead, it bears a mosaic of bony plates beneath its leathery skin, in general, sea turtles have a more fusiform body plan than their terrestrial or freshwater counterparts. The reduced volume of a body means sea turtles can not retract their head, legs. However this more stream-line body plan reduces drag in the water, the leatherback is the largest species of sea turtle. Measuring 2-3 meters in length, and 1-1.5 m in width, other species are smaller, being mostly 60-120 cm and proportionally narrower. Sea turtles, along with turtles and tortoises, are part of the order Testudines. All species except the leatherback are in the family Cheloniidae, the leatherback is the only extant member of the family Dermochelyidae. The origin of sea turtles back to the Late Jurassic with genera such as Plesiochelys. In Africa, the first marine turtle is Angolachelys, from the Turonian of Angola, however, neither of these are related to extant sea turtles, the oldest representative of the lineage leading to these was Desmatochelys padillai, from the Early Cretaceous. A lineage of unrelated marine testudines, the pleurodire bothremydids, also survived well into the Cenozoic, Sea turtles constitute a single radiation that became distinct from all other turtles at least 110 million years ago. The flatback sea turtle is found solely on the northern coast of Australia, the Kemps ridley sea turtle is found solely in the Gulf of Mexico and along the East Coast of the United States. Sea turtles are found in the waters over continental shelves. During the first three to five years of life, sea turtles spend most of their time in the pelagic zone floating in seaweed mats, Green sea turtles in particular are often found in Sargassum mats, in which they find shelter and food. Once the sea turtle has reached adulthood it moves closer to the shore, females will come ashore to lay their eggs on sandy beaches during the nesting season
11.
Shark
–
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha and are the group to the rays. Under this broader definition, the earliest known sharks date back to more than 420 million years ago, acanthodians are often referred to as spiny sharks, though they are not part of Chondrichthyes proper, they are a paraphyletic assemblage leading to cartilaginous fish as a whole. Since then, sharks have diversified into over 500 species, Sharks are found in all seas and are common to depths of 2,000 metres. They generally do not live in freshwater although there are a few exceptions, such as the bull shark and the river shark. Sharks have a covering of dermal denticles that protects their skin from damage and they have numerous sets of replaceable teeth. Well-known species such as the white shark, tiger shark, blue shark, mako shark. Many shark populations are threatened by human activities, until the 16th century, sharks were known to mariners as sea dogs. The etymology of the shark is uncertain. One theory is that it derives from the Yucatec Maya word xok, however, the Middle English Dictionary records an isolated occurrence of the word shark in a letter written by Thomas Beckington in 1442, which rules out a New World etymology. Evidence for the existence of sharks dates from the Ordovician period, 450–420 million years ago, before land vertebrates existed and before many plants had colonized the continents. Only scales have been recovered from the first sharks and not all agree that these are from true sharks. The oldest generally accepted shark scales are from about 420 million years ago, the first sharks looked very different from modern sharks. The majority of sharks can be traced back to around 100 million years ago. Most fossils are of teeth, often in large numbers, partial skeletons and even complete fossilized remains have been discovered. Estimates suggest that sharks grow tens of thousands of teeth over a lifetime, the teeth consist of easily fossilized calcium phosphate, an apatite. When a shark dies, the decomposing skeleton breaks up, scattering the apatite prisms, preservation requires rapid burial in bottom sediments. Among the most ancient and primitive sharks is Cladoselache, from about 370 million years ago, which has been found within Paleozoic strata in Ohio, Kentucky, and Tennessee
12.
Dolphin
–
Dolphins are a widely distributed and diverse group of aquatic mammals. They are a grouping within the order Cetacea, excluding whales and porpoises. The dolphins comprise the extant families Delphinidae, Platanistidae, Iniidae, and Pontoporiidae, there are 40 extant species of dolphins. Dolphins, alongside other cetaceans, belong to the clade Cetartiodactyla with even-toed ungulates and their closest living relatives are the hippopotamuses, having diverged about 40 million years ago. Dolphins range in size from the 1.7 m long and 50 kg Mauis dolphin to the 9.5 m and 10 t killer whale, several species exhibit sexual dimorphism, in that the males are larger than females. They have streamlined bodies and two limbs that are modified into flippers, though not quite as flexible as seals, some dolphins can travel at 55.5 km/h. Dolphins use their conical shaped teeth to capture fast moving prey and they have well-developed hearing which is adapted for both air and water and is so well developed that some can survive even if they are blind. Some species are adapted for diving to great depths. They have a layer of fat, or blubber, under the skin to keep warm in the cold water, although dolphins are widespread, most species prefer the warmer waters of the tropic zones, but some, like the right whale dolphin, prefer colder climates. Dolphins feed largely on fish and squid, but a few, like the killer whale, feed on large mammals, male dolphins typically mate with multiple females every year, but females only mate every two to three years. Calves are typically born in the spring and summer months and females bear all the responsibility for raising them, mothers of some species fast and nurse their young for a relatively long period of time. Dolphins produce a variety of vocalizations, usually in the form of clicks, Dolphins are sometimes hunted in places like Japan, in an activity known as dolphin drive hunting. Besides drive hunting, they face threats from bycatch, habitat loss. Dolphins have been depicted in cultures worldwide. Dolphins occasionally feature in literature and film, as in the film series Free Willy, Dolphins are sometimes kept in captivity and trained to perform tricks, but breeding success has been poor and the animals often die within a few months of capture. The most common dolphins kept are killer whales and bottlenose dolphins, the name is originally from Greek δελφίς, dolphin, which was related to the Greek δελφύς, womb. The animals name can therefore be interpreted as meaning a fish with a womb, the name was transmitted via the Latin delphinus, which in Medieval Latin became dolfinus and in Old French daulphin, which reintroduced the ph into the word. The term mereswine has also historically been used, the term dolphin can be used to refer to, under the parvorder Odontoceti, all the species in the family Delphinidae and the river dolphin families Iniidae, Pontoporiidae, Lipotidae and Platanistidae
