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Encyclopedia > Poikilotherm

Cold-blooded is an archaic term used to define organisms that maintaining their body temperatures in ways different from mammals and birds. Cold-blooded creatures were, initially, presumed to be incapable of maintain their body temperatures at all. They were presumed to be "slaves" to their environments. Whatever the environmental temperature was, so too, was their body temp. Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals characterized by the presence of mammary glands... Orders Many - see section below. ...


Since that time, advances in the study of how creatures maintain their internal temperatures (deemed: thermophysiology), have shown that many of the preconceived notions of what warm blooded and cold blooded mean, were far from accurate. Today scientists realize that body temperature types are not a simple matter of black and white. Most creatures fit more in line with a graded spectrum from one extreme (cold blooded) to another (warm blooded). Because of this, both of these terms have since fallen out of favour. They have been generally replaced with one, or more of their variants (see below: Breaking down Cold-Bloodedness) A warm-blooded (homeothermic) animal is one that can keep its core body temperature at a nearly constant level regardless of the temperature of the surrounding environment (that is, to maintain thermal homeostasis). ... A warm-blooded (homeothermic) animal is one that can keep its core body temperature at a nearly constant level regardless of the temperature of the surrounding environment (that is, to maintain thermal homeostasis). ...

Contents


Breaking down Cold-Bloodedness

Cold-bloodedness generally refers to three separate areas of thermoregulation. Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when temperature surrounding is very different. ...

  1. Ectothermy
  2. Poikilothermy
  3. Bradymetabolism
  • Ectothermy - This refers to creatures that control their body temperature through external means (Greek: ecto = "outside," therm = "heat"), such as the sun, or flowing air/water. For more on this see: #Types of temperature control
  • Poikilothermy - This refers to creatures whose internal temperatures vary; often matching the ambient temperature of the immediate environment (Greek: poikilos = "varied," therm = "heat").
  • Bradymetabolism - This term refers to the resting metabolism of a creature. If said creature has a low resting metabolism, it is considered to be bradymetabolic (Greek: brady = "slow," metabol = "to change"). Bradymetabolic animals can often undergo dramatic changes in metabolic speed, based off of food availability and temperature. Many bradymetabolic creatures in deserts, and areas that experience extreme winters, are capable of "shutting down" their metabolism and approach near death states, until favourable conditions return.
    • Note: It is important to keep in mind that a bradymetabolic animal has a low resting metabolism only. Their active metabolism is often many times higher. As such, a bradymetabolic creature should not be considered slow.

Few creatures actually fit all three of the criteria listed above. Most animals use a combination of these three aspects of thermophysiology, along with their counterparts (endothermy, homeothermy & tachymetabolism) to create a broad spectrum of body temperature types. Most of the time, creatures that use any one of the previously defined aspects, are usually pigeon-holed into the term: Cold-blooded. Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος (metabolismos), the Greek word for change, or overthrow (Etymonline)), is the biochemical modification of chemical compounds in living organisms and cells. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος (metabolismos), the Greek word for change, or overthrow (Etymonline)), is the biochemical modification of chemical compounds in living organisms and cells. ... Endothermic can mean: in chemistry, a type of process that absorbs heat from its surroundings. ... A warm-blooded (homeothermic) animal is one that can keep its core body temperature at a nearly constant level regardless of the temperature of the surrounding environment (that is, to maintain thermal homeostasis) . This can involve not only the ability to generate heat, but also the ability to cool down... Warm-blooded is an archaic term used to describe an animal that keeps its core body temperature at a nearly constant level regardless of the temperature of the surrounding environment (that is, to maintain thermal homeostasis). ...


Physiologists also coined the term heterothermy, for creatures that exhibit a unique case of poikilothermy. Greek: hetero = other thermy = heat. ...


Types of temperature control

Examples of this temperature control include:

  • Snakes and lizards sunning themselves on rocks.
  • Fish changing depths in the water column to find a suitable temperature.
  • Desert animals burrowing beneath the sand during the day.
  • Insects that warm their flight muscles by vibrating them in place.
  • Dilating or constricting peripheral blood vessels to adapt more or less quickly to the ambient temperature.

Many homeothermic, or warm-blooded, animals also make use of these techniques at times. For example, all animals are at risk of overheating on hot days in the desert sun, and most homeothermic animals can shiver. Superfamilies and Families Henophidia Aniliidae Anomochilidae Boidae Bolyeriidae Cylindrophiidae Loxocemidae Pythonidae Tropidophiidae Uropeltidae Xenopeltidae Typhlopoidea Anomalepididae Leptotyphlopidae Typhlopidae Xenophidia Acrochordidae Atractaspididae Colubridae Elapidae Hydrophiidae Viperidae Snakes are cold blooded legless reptiles closely related to lizards, which share the order Squamata. ... This page is about Lizards, the order of reptile. ... Atlantic herring, Clupea harengus, the most abundant fish species in the world. ... A dune in the Egyptian desert Desert in California In geography, a desert is a landscape form or region that receives little precipitation. ... A database query syntax error has occurred. ... The arterial system The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... A warm-blooded (homeothermic) animal is one that can keep its core body temperature at a nearly constant level regardless of the temperature of the surrounding environment (that is, to maintain thermal homeostasis) . This can involve not only the ability to generate heat, but also the ability to cool down...


Poikilotherms often have more complex metabolisms than homeotherms. For an important chemical reaction, poikilotherms may have four to ten enzyme systems that operate at different temperatures. As a result, poikilotherms often have larger, more complex genomes than homeotherms in the same ecological niche. Frogs are a notable example of this effect. Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = leaven) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... In ecology, a niche is a term describing the relational position of a species or population in an ecosystem. ... Pobblebonk, Australia Frogs are amphibians in the Order Anura, which includes frogs and toads. ...


Because their metabolism is so variable, poikilothermic animals do not easily support complex, high-energy organ systems such as brains or wings. Some of the most complex adaptations known involve poikilotherms with such organ systems. One example is the swimming muscles of Tuna, which are warmed by a heat exchanger. In general, poikilothermic animals do not use their metabolisms to heat or cool themselves. For the same body weight poikilotherms need 1/3 to 1/10 of the energy of homeotherms. They therefore eat only 1/3 to 1/10 of the food needed by homeothermic animals. Species Thunnus alalunga Thunnus albacares Thunnus atlanticus Thunnus maccoyii Thunnus obesus Thunnus orientalis Thunnus thynnus Thunnus tonggol Tuna are several species of ocean-dwelling fish in the family Scombridae, mostly in the genus Thunnus. ... A heat exchanger is a device for transferring heat from one fluid to another, where the fluids are separated by a solid wall so that they never mix. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος (metabolismos), the Greek word for change, or overthrow (Etymonline)), is the biochemical modification of chemical compounds in living organisms and cells. ...


Some larger poikilotherms, by virtue of their substantial volume to surface area ratio, are able to maintain relatively high body temperatures and high metabolic rates. This phenomenon, known as gigantothermy, has been observed in sea turtles and great white sharks, and was most likely present in many dinosaurs and ichthyosaurs. Volume (also called capacity) is a quantification of how much space an object occupies. ... This article explains the meaning of area as a Physical quantity. ... Santorio Santorio (1561-1636) in his steelyard balance, from Ars de statica medecina, first published 1614 Metabolism (from μεταβολισμος (metabolismos), the Greek word for change, or overthrow (Etymonline)), is the biochemical modification of chemical compounds in living organisms and cells. ... Wikipedia does not have an article with this exact name. ... Genera Caretta Lepidochelys Chelonia Eretmochelys Natator Dermochelys Sea turtles are large, ocean-dwelling turtles. ... Binomial name Carcharodon carcharias (Linnaeus, 1758) The Great White Shark (Carcharodon carcharias), also known as White Pointer, White Shark or Amaletz, is an exceptionally large lamniform shark found in coastal surface waters in all major oceans. ... Orders Saurischia    Sauropodomorpha    Theropoda Ornithischia Dinosaurs are giant reptiles that dominated the terrestrial ecosystem for most of their 165-million year existence. ... Ichthyosaurs (Greek for fish lizards) were giant marine reptiles that resemble a dolphin with teeth (see convergent evolution). ...


Ecological niches

It is comparatively easy for a poikilotherm to accumulate enough energy to reproduce. Poikilotherms in the same ecological niche often have much shorter generations than homeotherms: weeks rather than years.


This energy difference also means that a given niche of a given ecology can support three to ten times the number of poikilothermic animals as homeothermic animals. However, in a given niche, homeotherms often drive poikilothermic competitors to extinction because homeotherms can gather food for a greater fraction of each day.


Poikilotherms succeed in some niches, such as islands, or distinct bioregions (such as the small bioregions of the Amazon basin). These often do not have enough food to support a viable breeding population of homeothermic animals. In these niches, poikilotherms such as large lizards, crabs and frogs supplant homeotherms such as birds and mammals. An ecoregion is a relatively large area of land or water that contains a geographically distinct assemblage of natural communities. ... emine ==Geography== The South American rainforest of Amazonia (60% located in Brazil), the largest in the world, was originally covered by more than 7,000,000 km² (2 million square miles) of dense tropical forest. ...


See also

  • Warm-blooded for organisms that fall in between both catagories.

A warm-blooded (homeothermic) animal is one that can keep its core body temperature at a nearly constant level regardless of the temperature of the surrounding environment (that is, to maintain thermal homeostasis) . This can involve not only the ability to generate heat, but also the ability to cool down...

External Links


  Results from FactBites:
 
Cold-blooded at AllExperts (1016 words)
One example is the swimming muscles of Tuna, which are warmed by a heat exchanger.In general, poikilothermic animals do not use their metabolisms to heat or cool themselves.
Some larger poikilotherms, by virtue of their substantial volume to surface area ratio, are able to maintain relatively high body temperatures and high metabolic rates.
Poikilotherms succeed in some niches, such as islands, or distinct bioregions (such as the small bioregions of the Amazon basin).
  More results at FactBites »

 
 

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