are sharks warm blooded animals?
112066
Sharks in general are poikilotherms or ectotherms (their body temperature is similar to the temperature of the surrounding water). \nHowever, some species (high-power fast swimmers belonging to family Lamnidae, such as genus Alopias -thresher sharks- and Lamna - porbeagle and others- ) have partial endothermy. That is, they're able to "hoard" the heat generated by muscle activity and therefore achieve differential temperature zones in their bodies, which are some degrees above water temperature. This is achieved by means of special countercurrent blood vessels and rete mirabilia. \nSome typical body parts that are kept warmer are the brain and eyes, the swimming muscles, and the "core" with the visceral organs, which is logical given that higher temperature allows a higher metabolic rate of these important organs.\n\n---------------------\nAmy: not only sharks, also tuna and related bony fishes are endotherms. And some reptiles too.\n------------------\nNew update: Wow, this question keeps getting answers that state that only  birds and mammals are endotherms. Please, people, if this is what they taught you at school, try to investigate a little further. Of course MOST sharks are "cold-blooded" (that is not the happiest term, it's better to say ectotherm - meaning that it gets its body heat from outside - or poikilotherm - meaning that body temperature is variable). But endothermy is an advantageous trait, and it has evolved independently in many animal groups.
788728
Yes. \n\nThe vast majority of paleontologists believe that anatotitan, like all dinosaurs, was warm-blooded. The definition of a warm-blooded creature is one which is able to regulate it's own body temperature.
9530
Sharks have sharp teeth because to kill animals/preys quickly and to avoid the preys from escaping with little injuries.\n\nIf the teeth were not sharp, how would sharks kill \npreys if the preys are virtually unhurt bacause of blunt teeth?\n\nAlso, God made the teeth sharp so that the killing will be quick and less painful.\n\nSharp teeth made sharks hydrodynamically superquick. Teeth covering their bodies make that happen.\n\nWith very sharp teeth, sharks do not have to exert big bite force to kill preys.
550793
With great difficulty. Penguins tend to huddle together to stay warm. Polar bears have black skin and hollow quill like fur that collects sun energy like a solar water heater. Nature has adapted many polar animals, and even Eskimos with unique abilities that are very individualized for survival.\nGreat question!
114432
Ok, I know that the bit about sharks not breathing if they're still is still taught at school, and essentially it has some point. It's true that gill oxygenation is better when the water flow through the branchial area is greater. \nBut sharks DO indeed stop swimming, they can rest near the bottom of the ocean (as if sleeping) and they use the pumping motion of the floor of their mouth (their mostly immobile tongue) to help water move through the gills. \nBut as I've said, immobile sharks lie mostly near the ocean floor. This is because they're rather dense with respect to water (they don't have swimming bladders like bony fishes do), although their enormous, fat-filled liver increases their buoyancy significantly (along with other physiological characteristics). When they swim, sharks can keep themselves in midwater; the movements of the trunk and tail generate the necessary thrust to keep them from falling to the bottom.
523945
Based on the accumulating evidence, mammals, birds, and dinosaurs all evolved from reptiles.  In fact, mammals are way older than birds and were contemporary with the dinosaurs.\n\nThe other evidence is that reptiles evolved to fill all ecological niches including the oceans (ichthyosaurs and plesiosaurs, turtles, and crocodilians), the skies (pterosaurs), and dominant land animals (dinosaurs).\n\nThey have given live birth (ichthyosaurs), they've been cold blooded and warm blooded (dinosaurs).\n\nI guess the point is that you could go simplistic and make your race not very far evolved from what we think of as reptiles (scaly skin which must be shed, egg laying, cold blooded, forked tongue (snakes)).\n\nOr you could make the race some step in some other direction, scales but with mammary glands, warm blooded, with feathers kind of like velociraptor.  Maybe they developed the truncated rib-cage like that of mammals which allows for tortional twists."\n\nWhat if monkeys were marsupial with scaley skin and they killed their prey by sepsis caused by the nasty bacteria that live in their mouth transfered when they bite their prey (like komodo dragons)?  What if these creatures were the progenitors of humanoid reptiles?
1058660
The Australian salt water crocodile is a ferocious predater.\nSo is the great white shark.\nSalty's often swim great distances out to sea. (especially, off of Queensland Austraia.\nThe shark has an advantage because it does not have to surface for air.\nSteve Irwin got some great footage of just such a battle, & screened it on his show "crocodile hunter".. The shark lost a pectoral fin and almost was killed. But the salty surfaced for a gulp of air and was nailed by the shark for his moment's inattention.
193151
white sharks,tiger sharks and zambesi bull shark\n\n\nAt least 34 species of sharks have been recorded off the Pacific Coast of North America.  These are listed in their hypothesized phylogenetic sequence with notes on their known geographic distribution off the West Coast.  Those known or strongly suspected to have attacked humans are marked in red\n\nOrder Chlamydoselachiformes\nFamily Chlamydoselachidae\nChlamydoselachus anguineus - Frilled Shark\nonly one Pacific Coast record:  Pt. Arguello, California\n\nOrder Hexanchiformes\nFamily Notorynchidae\nNotorynchus cepedianus - Broadnose Sevengill Shark\nBritish Columbia to Gulf of California; most abundant off Central California\n\nFamily Hexanchidae\nHexanchus griseus - Bluntnose Sixgill Shark\nAlaska to Bahia de Todos Santos, northern Baja California\n\nOrder Echinorhiniformes\nFamily Echinorhinidae\nEchinorhinus cookei - Prickly Shark\nMoolach Beach, Oregon, to Baja California and Gulf of California\n\nOrder Squaliformes\nFamily Squalidae\nSqualus acanthias - Spiny Dogfish\nBering Sea and Alaska to central Baja California\n\nFamily Etmopteridae\nCentroscyllium nigrum - Combtooth Dogfish\nSouthern California to Strait of Magellan, Chile\n\nFamily Somniosidae\nSomniosus pacificus - Pacific Sleeper Shark\nBering Sea and Alaska to Baja California; in shallow waters in northern part of its range, but in deep water from California southward\n\nFamily Dalatiidae\nEuprotomicrus bispinatus - Pygmy Shark\nrare off California; found well offshore\n\nIsistius brasiliensis - Cookiecutter Shark\nBaja California south to Isla Galapagos\n\nOrder Squaltiniformes\nFamily Squatinidae\nSquatina californica - Pacific Angel Shark\nsouthern Alaska to Baja California and Gulf of California; to depth of 186 meters in Gulf of California\n\nOrder Heterodontiformes\nFamily Heterodontidae\nHeterodontus francisci - Horn Shark\nCentral California to Gulf of California and southward, probably to Ecuador and Peru; rare north of Southern California\n\nHeterodontus mexicanus - Mexican Horn Shark\nBahia Magdalena, southern Baja California, into the Gulf of California and southward to Peru\n\nOrder Orectolobiformes\nFamily Rhincodontidae\nRhincodon typus - Whale Shark\noccasionally off Southern California\n\nFamily Ginglymostomatidae\nGinglymostoma cirratum - Nurse Shark\nsouthern Baja California into Gulf of California and southward to Peru\n\nOrder Lamniformes\nFamily Mitsukurinidae\nMitsukurina owstoni - Goblin Shark\nonly one Pacific Coast record, from Southern California\n\nFamily Odontaspididae\nOdontaspis ferox - Ragged-Tooth Shark\nSouthern California and Malpelo Island, Mexico\n\nFamily Megachasmidae\nMegachasma pelagios - Megamouth Shark\nSouthern California\n\nFamily Alopiidae\nAlopias pelagicus - Pelagic Thresher\nSouthern California southward; oceanic, epipelagic\n\nAlopias superciliosus - Bigeye Thresher Shark\nCalifornia to Gulf of California\n\nAlopias vulpinus - Common Thresher\nGoose Bay, British Columbia, to Chile\n\nAlopias sp. - [undescribed species of thresher shark]\nknown only from Southern California\n\nFamily Pseudocarchariidae\nPseudocarcharias kamoharai - Crocodile Shark\nprobably off Southern California\n\nFamily Cetorhinidae\nCetorhinus maximus - Basking Shark\nAleutian Islands and Gulf of Alaska to Gulf of California\n\nFamily Lamnidae\nLamna ditropis - Salmon Shark\nBering Sea and Gulf of Alaska to central Baja California\n\nCarcharodon carcharias - White Shark\nGulf of Alaska to Gulf of California, mostly shallow coastal waters\n\nIsurus oxyrinchus - Shortfin Mako\nBritish Columbia to Chile\n\nOrder Carcharhiniformes\nFamily Scyliorhinidae\nApristurus brunneus - Brown Catshark\nsoutheastern Alaska to northern Baja California; deep (137-1298 meters)\n\nApristurus kampae - Longnose Catshark\nCape Blanco, Oregon, southward to Southern California and Gulf of California;deep (180-1888 meters)\n\nCephaloscyllium ventriosum - Swell Shark\nMonterey Bay, Central California, to Acapulco,
74215
I agree with big brain, they are some of the most efficent and dangerous killers in the animal kingdom. \n\nAlthough they do have communication patterns. Male crocodiles let out a low grunt when they are searching for a mate. And baby crocodiles let out a high pitch grunt when they are in danger. Not too sure about the sharks though.\n\nMost of the time though as big brain said they are solitary animals.
104497
never heard of sharks being mans best friends but I have heard of dogs being mans best friend and I know thats true at least for me. I love dogs but sharks not so much at all they need to come up with something better then that. Maybe instead of sharks they should say dolphins I love dolphins there sooo cute.
112408
Yes sharks kill people unless a person shoves another person in a sharks mouth
570841
fish, sharks , whales, crustaceans of all types.
534138
The whale shark. Whales and dolphins are not fish but mammals. Whale sharks look pretty scary but are actually filter feeders, they do not bite.
311429
Sleep is one of the last bastions of mystery that Science has yet to conquer. Despite several centuries of study, speculation, and debate, we still really don't know what sleep is or why we need to 'shut down' periodically. We know that all sorts of vertebrate animals – mammals, birds, reptiles, and at least some fishes – periodically enter a period of torpor characterized by a profound change in brain waves.\n\nBut when it comes to whether or not sharks sleep, we just don't know. There have been reports from all over the globe, including Mexico, Japan, and Australia, of sharks resting motionless in caves. These have been called "sleeping sharks", but I can attest that the eyes of these quiescent sharks do follow divers moving about in the caves with them, so they're definitely not asleep.\n\nIn his sweeping epic Paradise Lost, 17th Century English poet, John Milton, asked, "What hath night to do with sleep?" We know from sonic telemetry studies (the underwater equivalent of radio tracking) that at least some shark species -- such as the Reef Whitetip (Triaenodon obesus) and the Tiger Shark (Galeocerdo cuvier) -- are actually more active at night than during the day. Since schooling behavior is partially coordinated by vision, many other sharks are most active at dawn and dusk, when such prey is at a disadvantage. Studies such as these suggest that at least some sharks do not sleep at night.\n\nWe used to think that the Great White Shark (Carcharodon carcharias) was primarily active during the day. But it turns out that this is largely due to observer bias: humans tend to be diurnal rather than nocturnal, and it's very difficult to watch an underwater creature at night. Recent experiments by Peter Klimley using stationary telemetry pods placed along the bottom at the Farallon Islands, we have learned that White Sharks are quite active at night, when they probably feed primarily on bottom fishes. If these bottom fishes are sleeping when attacked, they're certainly in for a 'rude awakening'!\n\nBecause sharks rely on ram-ventilation -- that is, their forward swimming to push oxygen-bearing water through their mouths and over their gills -- this fact begs the question: do sharks sleep at all? Dolphins are conscious breathers, actually having to think about rising to the surface, opening their blowholes, and breathing. From Russian studies carried out in the early 1970's, we know that dolphins catnap in 2 to 3-minute stretches, actually shutting down one hemisphere of their brain at a time. From experiments carried out on a small shark called the Spiny Dogfish (Squalus acanthias), we know that the 'Central Pattern Generator' that co-ordinates swimming movements in sharks is not located in the brain, but in the spinal chord. Thus, it is possible for an unconscious shark to swim.\n\nThere is even a possibility that the sharks' fore, mid-, and hind- brain shut down in sequence, resulting in the shark equivalent of sleep-walking.\n\nI hope this answers your question.
753941
They are mammals, so they have lungs and can not absorb enough oxygen to survive.  Dolphins evolve from a land animal that return to the sea.  There is a belief that dolphins can absorb oxygen from the sea, but because they are warm blooded, they require large amount of oxygen, which sea water can't provide. Many warm blooded animals evolve to become sea creature, because of the abundents of food.  Warm blooded animals are smarter and in some ways faster than cold water animals, gave an incentive for some species to become sea creatures.  Warm blooded animals though require large quantity of oxygen to run its supercharged matabolism, which why fish never evolve into being warm blooded.
432907
Is there a reason you're asking this question under a new name?  Did you not like the previous answers?\n\nMy answer from: \n\nhttp://answers.yahoo.com/question/index;_ylt=Aosgux8O5O_.4Y0ThAeGgyjsy6IX?qid=1006041806251\n\nSome sharks are very slow and the average person can easily outswim them, at least for the short term. Sharks probably have better stamina and would eventually catch up.\n\nRemember, sharks are a very diverse group. There are huge, filter-feeding whale sharks and tiny little miniature dogfish. Everything from the weird cookie-cutter sharks to the weirder goblin shark.\n\nGuitarfish are especially slow sharks, if I remember correctly.\n\nYour real question is, Will someone ever be born who can outswim the *fastest* shark. The answer is probably no. We are not well designed for life in the water and our swimming is extremely clumsy. Evolution has no reason to fix any of these problems given we are resolutely terrestrial.
214023
snail being a mammal is warm blooded