Mammals that live in water are known aquatic mammals. On the other words, aquatic mammals is a diverse group of mammals which completes their life-cycle (all or most) in water. Example: Dolphin, Whales, Manatee, Seals, Sea Lions, Walrus, Dugong, Hippopotamus
Aquatic animal
Animals that live in water are known aquatic animals. On the other words, an aquatic animal is an animal which completes their life-cycle (all or most) in water. Example: Fishes, Turtles, Crocodiles, Dolphins, Whales etc. of vertebrates and Jelly fishes,
Aquatic birds
Birds that live (feeding, breeding, staying) on or around water (aquatic environment) are known aquatic birds. On the other hand, birds that depend on aquatic environment to complete their life-cycle are called aquatic birds. They are developed and adapted to
Aestivation
Aestivation (also spelled “estivation”) is a situation of inactivity and a lowered metabolic rate of animal during summer as well as dry season. Most of all coldblooded (also known poikilothermic or ectothermic) animals take position in the time of hotness
Amphibians
Amphibians (singular: amphibian) are cold-blooded vertebrates (usually tetrapod/four-footed, carnivorous and oviparous) which young are commonly under go metamorphosis from water-breathing larva with gills to an air-breathing adult with lungs. They use their soft, moist, glandular scale-less skin as an accessory
Amphibia
Amphibia is the group (Class) of vertebrates that includes amphibians (singular: amphibian). The word Amphibia consists of Greek word “amphi” meaning “on both side” and “bios” meaning life. Amphibians (singular: amphibian) are cold-blooded vertebrates (usually tetrapod/four-footed, carnivorous and oviparous) which
Acoelomata
Acoelomata is the group that includes acoelomates. Acoelomates (singular: acoelomate) means a group of animals that lacks fluid filled body cavity named coelom. Body cavity (the space between outer side of alimentary canal and inner side of body wall) of
Acoelom
Acoelom means a body cavity which is filled with cell and tissue in place of body fluid. It is lacking of body fluid and also lacking of peritoneum. An animal having acoelom (means having no fluid filled coelom) is called
Accessory respiratory organ
An organ that allows some fishes (air breathing fishes) to takes oxygen directly from the air. Such as skin of Anguilla anguilla, pharyngeal diverticula of snakeheads, tubular air sac and arborescent organ of some catfishes, labyrinthine organ of climbing perch,
Arrector pili
Arrector pili (plural: arrectores pilorum) is a small fan-shaped smooth muscle attached to each hair follicle in mammals. The hair stands on end when the muscle contracts. অ্যারেক্টর পিলি: স্তন্যপায়ীদের প্রতিটি লোম একটি লোমকূপের (Hair follicle) মধ্যে অবস্থান
Acoelomate
Acoelomate (plural acoelomates) means an animal that lacks a fluid filled body cavity named coelom. Body cavity (the space between outer side of alimentary canal and inner side of body wall) of acoelomates is filled with mesodermal cell as well
Acrania
Acrania or Acraniata is a group of chordates which have no skull or cranium, head, brain, vertebral column and jaws but have notochord. All are marine, small in size and treated as lower or primitive chordates. This group is divided