AQUARIUM FISHES:-
Sunday, September 21, 2008
WHALE
WHALE:-Whales are cetaceans which are neither dolphins (i.e. members of the families Delphinidae or Platanistoidae) nor porpoises. Orcas (Killer Whales) and Pilot whales have "whale" in their name, but they are dolphins for the purpose of classification.The term whale is also sometimes used to refer to all cetaceans or just larger cetaceans.
Whales in culture:-Whale weather-vane atop the Nantucket Historical Association Whaling Museum.Whales are frequently portrayed in literature as violent creatures who attack shipping and kill or eat sailors, despite overwhelming scientific evidence to the contrary. This is especially true in literature written prior to the modern scientific study of the creatures, or in period literature. A common whale-themed plot device concerns mariners who are swallowed whole by a whale, and find themselves trapped alive in the creature's belly. In some instances, the victims of these encounters are able to escape, often by causing the whale sufficient gastronomic distress that it is forced to expel them; in other such occurrences in fiction, the victim is doomed.
Behavior:-A Humpback Whale breaching.
Whales are widely classed as predators, but their food ranges from microscopic plankton to very large fish. Males are called bulls; females, cows. The young are called calves.
As mammals, whales breathe air and must surface to get oxygen. This is done through a blowhole. Many whales also exhibit other surfacing behaviours such as breaching and tail slapping.
Because of their environment (and unlike many animals), whales are conscious breathers: they decide when to breathe. All mammals sleep, including whales, but they cannot afford to fall into an unconscious state for too long, since they need to be conscious in order to breathe. It is thought that only one hemisphere of their brains sleeps at a time, so that whales are never completely asleep, but still get the rest they need. This is thought because whales often sleep with only one eye closed
Human effects:-
Whaling
Main article: Whaling
A fossil whale bone found at California Beach
World map of International Whaling Commission (IWC) members/non-memberscountries in blue
World population graph of Blue Whales
Eighteenth century engraving of Dutch whalers hunting Bowhead Whales in the Arctic. Beerenberg on Jan Mayen Land can be seen in the background.
Some species of large whales are endangered as a result of commercial whaling from the eleventh century to the twentieth. For centuries large whales have been hunted for oil, meat, baleen and ambergris (a perfume ingredient from the intestine of sperm whales). By the middle of the 20th century, whaling left many populations severely depleted.
The International Whaling Commission introduced a six year moratorium on all commercial whaling in 1986, which has been extended to the present day. For various reasons some exceptions to this moratorium exist; current whaling nations are Norway, Iceland and Japan and the aboriginal communities of Siberia, Alaska and northern Canada. For details, see whaling.
Whaling
Main article: Whaling
A fossil whale bone found at California Beach
World map of International Whaling Commission (IWC) members/non-memberscountries in blue
World population graph of Blue Whales
Eighteenth century engraving of Dutch whalers hunting Bowhead Whales in the Arctic. Beerenberg on Jan Mayen Land can be seen in the background.
Some species of large whales are endangered as a result of commercial whaling from the eleventh century to the twentieth. For centuries large whales have been hunted for oil, meat, baleen and ambergris (a perfume ingredient from the intestine of sperm whales). By the middle of the 20th century, whaling left many populations severely depleted.
The International Whaling Commission introduced a six year moratorium on all commercial whaling in 1986, which has been extended to the present day. For various reasons some exceptions to this moratorium exist; current whaling nations are Norway, Iceland and Japan and the aboriginal communities of Siberia, Alaska and northern Canada. For details, see whaling.
Saturday, September 13, 2008
SEAHORSE
Seahorses:-
are a genus (Hippocampus) of fish belonging to the family Syngnathidae, which also includes pipefish and leafy sea dragons. There are over 32 species of seahorse, mainly found in shallow tropical and temperate waters throughout the world. They prefer to live in sheltered areas such as sea grass beds, coral reefs, or mangroves. Colonies have been found in European waters such as the Thames Estuary.[2] From North America down to South America there are approximately four species, ranging from very small in size (dwarf seahorses are only about an inch long) to those much larger, found off the Pacific Coast of Central America (the foot-long Hippocampus ingens). Hippocampus erectus are larger seahorses found anywhere from Nova Scotia down to around Uruguay. These fish form territories, with males staying in about one square meter of their habitat while females range about one hundred times that area. They bob around in sea grass meadows, mangrove stands, and coral reefs where they are camouflaged by murky brown and grey patterns that blend into the sea grass backgrounds. During social moments or in unusual surroundings, seahorses turn bright colors. According to co-founder of Project Seahorse, Amanda J. Vincent, mates can blush a shade of creamy yellow when meeting each other in the morning. She even encountered one male who took the shade of the orange tape she used to mark the grid in the study area. [3]
Physical description:-
Seahorses are so named for their equine appearance. Although they are fish, they do not have scales, rather a thin skin stretched over a series of bony plates arranged in rings throughout their body. Each species has a distinct number of rings. Seahorses swim upright, another characteristic that is not shared by their fish relatives who swim horizontally. Seahorses have a coronet on their head, which is distinct to each seahorse, much like a human fingerprint. They swim very poorly by using a dorsal fin, which they rapidly flutter to propel them, and pectoral fins, located behind their eyes, which they use to steer. Because they are poor swimmers, they are most likely to be found resting in sea grasses or coral reefs with their prehensile tails wound around a stationary object. They have long snouts, which they use to suck up food, and eyes that can move independently of each other much like a chameleon. Seahorses eat small shrimp, tiny fish and plankton
Evolution and Fossil Record:-
Anatomical evidence, supported by molecular and genetic evidence, demonstrates that seahorses are highly modified pipefish. The fossil record of seahorses, however, is very sparse. The best known, and best studied fossils are from the Marecchia River Formation of Rimini Province, Italy, dating back to the Lower Pliocene, about 3 million years ago. The earliest known seahorse fossils are of a pipefish-like species from the "Coprolitic Horizon" of Tunjice hills, a lower Miocene lagerstatten in Slovenia dating back about 13 million years
are a genus (Hippocampus) of fish belonging to the family Syngnathidae, which also includes pipefish and leafy sea dragons. There are over 32 species of seahorse, mainly found in shallow tropical and temperate waters throughout the world. They prefer to live in sheltered areas such as sea grass beds, coral reefs, or mangroves. Colonies have been found in European waters such as the Thames Estuary.[2] From North America down to South America there are approximately four species, ranging from very small in size (dwarf seahorses are only about an inch long) to those much larger, found off the Pacific Coast of Central America (the foot-long Hippocampus ingens). Hippocampus erectus are larger seahorses found anywhere from Nova Scotia down to around Uruguay. These fish form territories, with males staying in about one square meter of their habitat while females range about one hundred times that area. They bob around in sea grass meadows, mangrove stands, and coral reefs where they are camouflaged by murky brown and grey patterns that blend into the sea grass backgrounds. During social moments or in unusual surroundings, seahorses turn bright colors. According to co-founder of Project Seahorse, Amanda J. Vincent, mates can blush a shade of creamy yellow when meeting each other in the morning. She even encountered one male who took the shade of the orange tape she used to mark the grid in the study area. [3]
Physical description:-
Seahorses are so named for their equine appearance. Although they are fish, they do not have scales, rather a thin skin stretched over a series of bony plates arranged in rings throughout their body. Each species has a distinct number of rings. Seahorses swim upright, another characteristic that is not shared by their fish relatives who swim horizontally. Seahorses have a coronet on their head, which is distinct to each seahorse, much like a human fingerprint. They swim very poorly by using a dorsal fin, which they rapidly flutter to propel them, and pectoral fins, located behind their eyes, which they use to steer. Because they are poor swimmers, they are most likely to be found resting in sea grasses or coral reefs with their prehensile tails wound around a stationary object. They have long snouts, which they use to suck up food, and eyes that can move independently of each other much like a chameleon. Seahorses eat small shrimp, tiny fish and plankton
Evolution and Fossil Record:-
Anatomical evidence, supported by molecular and genetic evidence, demonstrates that seahorses are highly modified pipefish. The fossil record of seahorses, however, is very sparse. The best known, and best studied fossils are from the Marecchia River Formation of Rimini Province, Italy, dating back to the Lower Pliocene, about 3 million years ago. The earliest known seahorse fossils are of a pipefish-like species from the "Coprolitic Horizon" of Tunjice hills, a lower Miocene lagerstatten in Slovenia dating back about 13 million years
BLUEWHALE
The Blue whale:-is a marine mammal belonging to the suborder of baleen whales (called Mysticeti).[3] At up to 33.59 metres (110 ft 2.5 in) in length and 181 metric tonnes tons)or more in weight, it is believed to be the largest animal ever to have existed.Long and slender, the Blue Whale's body can be various shades of bluish-grey dorsally and somewhat lighter underneath.[6] There are at least three distinct subspecies: B. m. musculus of the north Atlantic and north Pacific, B. m. intermedia, of the Southern Ocean and B. m. brevicauda (also known as the Pygmy Blue Whale) found in the Indian Ocean and South Pacific Ocean. B. m. indica, found in the Indian Ocean, may be another subspecies. As with other baleen whales, its diet consists mainly of small crustaceans known as krill, as well as small fish and sometimes squid.
Taxonomy:-also: Evolution of cetaceans
Blue Whales are rorquals (family Balaenopteridae), a family that includes the Humpback Whale, the Fin Whale, Bryde's Whale, the Sei Whale and the Minke Whale.[3] The family Balaenopteridae is believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Oligocene. However, it is not known when the members of those families diverged from each other. The Blue Whale is usually classified as one of seven species of whale in the genus Balaenoptera; one authority placed it in a separate monotypic genus Sibbaldus,[10] but this was not accepted elsewhere.[1] DNA sequencing analysis indicates that Blue Whales are phylogenetically closer to the Humpback (Megaptera) and the Gray Whale (Eschrichtius) than to other Balaenoptera species. If further research confirms these relationships, it will be necessary to reclassify the rorquals.
Feeding:-Blue Whales feed almost exclusively on krill, though they also take small numbers of copepods.[24] The species of this zooplankton eaten by Blue Whales varies from ocean to ocean. In the North Atlantic Meganyctiphanes norvegica, Thysanoessa raschii, Thysanoessa inermis and Thysanoessa longicaudata are the usual food.[25][26][27] In the North Pacific Euphausia pacifica, Thysanoessa inermis, Thysanoessa longipes, Thysanoessa spinifera, Nyctiphanes symplex and Nematoscelis megalops;[28][29][30] in the Antarctic Euphausia superba, Euphausia crystallorophias and Euphausia valentin
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