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Tadpole ALPHAbook 1
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found in adult amphibians such as a lateral line, gills and swimming tails. As they undergo metamorphosis, they start to develop functional lungs for breathing air, and the diet of tadpoles changes drastically. A few amphibians, such as some members of the frog family Brevicipitidae, undergo direct development i.e., they do not undergo a free-living larval stage as tadpoles instead emerging from eggs as fully formed "froglet" miniatures of the adult morphology. Some other species hatch into tadpoles underneath the skin of the female adult or are kept in a pouch until after metamorphosis. Having no hard skeletons, it might be expected that tadpole fossils would not exist. However, traces of biofilms have been preserved and fossil tadpoles have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biofilm
A biofilm comprises any syntrophic consortium of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix that is composed of extracellular polymeric substances (EPSs). The cells within the biofilm produce the EPS components, which are typically a polymeric conglomeration of extracellular polysaccharides, proteins, lipids and DNA. Because they have three-dimensional structure and represent a community lifestyle for microorganisms, they have been metaphorically described as "cities for microbes". Biofilms may form on living or non-living surfaces and can be prevalent in natural, industrial, and hospital settings. They may constitute a microbiome or be a portion of it. The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single cells that may float or swim in a liquid medium. Biofilms can form ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spiracle (vertebrates)
Spiracles () are openings on the surface of some animals, which usually lead to respiratory systems. The spiracle is a small hole behind each eye that opens to the mouth in some fish. In the jawless fish, the first gill opening immediately behind the mouth is essentially similar to the other gill opening. With the evolution of the jaw in the early jawed vertebrates, this gill slit was caught between the forward gill-rod (now functioning as the jaw) and the next rod, the hyomandibular bone, supporting the jaw hinge and anchoring the jaw to the skull proper. The gill opening was closed off from below, the remaining opening was small and hole-like, and is termed a spiracle. In many species of sharks and all rays the spiracle is responsible for the intake of water into the buccal space before being expelled from the gills. The spiracle is often located towards the top of the animal allowing breathing even while the animal is mostly buried under sediments. As sharks adapted a faster ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operculum (fish)
The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. Anatomy The opercular series contains four bone segments known as the preoperculum, suboperculum, interoperculum and operculum. The preoperculum is a crescent-shaped structure that has a series of ridges directed posterodorsally to the organisms canal pores. The preoperculum can be located through an exposed condyle that is present immediately under its ventral margin; it also borders the operculum, suboperculum, and interoperculum posteriorly. The suboperculum is rectangular in shape in most bony fishy and is located ventral to the preoperculum and operculum components. It is the thinnest bone segment out of the opercular series and is located directly above the gills. The interoperculum is triangular shaped and borders the suboperculum posterodorsally and the preoperculum anterodorsa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lateral Undulation
Undulatory locomotion is the type of motion characterized by wave-like movement patterns that act to propel an animal forward. Examples of this type of gait include crawling in snakes, or swimming in the lamprey. Although this is typically the type of gait utilized by limbless animals, some creatures with limbs, such as the salamander, forgo use of their legs in certain environments and exhibit undulatory locomotion. In robotics this movement strategy is studied in order to create novel robotic devices capable of traversing a variety of environments. Environmental interactions In limbless locomotion, forward locomotion is generated by propagating flexural waves along the length of the animal's body. Forces generated between the animal and surrounding environment lead to a generation of alternating sideways forces that act to move the animal forward. These forces generate thrust and drag. Hydrodynamics Simulation predicts that thrust and drag are dominated by viscous forces a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tadpoles 10 Days
A tadpole is the larval stage in the biological life cycle of an amphibian. Most tadpoles are fully aquatic, though some species of amphibians have tadpoles that are terrestrial. Tadpoles have some fish-like features that may not be found in adult amphibians such as a lateral line, gills and swimming tails. As they undergo metamorphosis, they start to develop functional lungs for breathing air, and the diet of tadpoles changes drastically. A few amphibians, such as some members of the frog family Brevicipitidae, undergo direct development i.e., they do not undergo a free-living larval stage as tadpoles instead emerging from eggs as fully formed "froglet" miniatures of the adult morphology. Some other species hatch into tadpoles underneath the skin of the female adult or are kept in a pouch until after metamorphosis. Having no hard skeletons, it might be expected that tadpole fossils would not exist. However, traces of biofilms have been preserved and fossil tadpoles have been ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Probreviceps
''Probreviceps'' is a small genus of brevicipitine frogs with only six members. They occur in the montane forests of Tanzania, Zimbabwe, and possibly Mozambique. They are sometimes known as the forest frogs, forest rain frogs, big-fingered frogs, or primitive rain frogs. Description ''Probreviceps'' are burrowing frogs with short limbs and direct development (i.e., there is no free-living larval stage); the eggs are deposited in burrows. Maximum snout–vent length is between in males and between in females, depending on the species. Males often have larger tympani than females. No discs are present on fingers or toes. Species identification is based on male advertisement calls, features of hands and feet, and distribution. Species There are six recognized species: * ''Probreviceps durirostris'', Snouted forest frog * ''Probreviceps loveridgei'', Loveridge's forest frog * ''Probreviceps macrodactylus'', Large-fingered forest frog * ''Probreviceps rhodesianus'', Highland fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Breviceps
''Breviceps'' is a genus of frogs in the family Brevicipitidae. Species in the genus ''Breviceps'' are commonly known as rain frogs or short-headed frogs. They occur in arid to semiarid climates of East Africa and Southern Africa. Taxonomy The genus ''Breviceps'' consists of 20 species, of which most occur in southern Africa. There are five species found in the Western Cape, '' B. gibbosus'', '' B. fuscus'' (black rain frog), '' B. rosei'' (Rose's rain frog), '' B. montanus'' (mountain rain frog) and '' B. acutirostris'' (strawberry rain frog). Two species are found in arid areas and other species are found in the eastern and northern parts of southern Africa. Description Species of the genus ''Breviceps'' are sexually dimorphic: males are much smaller than females. This prevents normal amplexus; instead, males and females produce an adhesive secretion from the skin that allows them to "stick" together during mating. Ecology and behaviour Species of the genus ''Breviceps'' sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Poll (livestock)
The poll is a name of the part of an animal's head, alternatively referencing a point immediately behind or right between the ears. This area of the anatomy is of particular significance for the horse. Specifically, the "poll" refers to the occipital protrusion at the back of the skull. However, in common usage, many horsemen refer to the poll joint, between the atlas (C1) and skull as the poll. The area at the joint has a slight depression, and is a sensitive location. Thus, because the crownpiece of a bridle passes over the poll joint, a rider can indirectly exert pressure on the horse's poll by means of the reins, bit, and bridle. Importance of the poll in riding The poll is especially important in riding, as ''correct'' flexion at the poll joint is a sign that the horse is properly on the bit. Over-flexion, with the poll lowered and the neck bent at a cervical vertebra farther down the neck, is usually a sign that the horse is either evading contact or that the rider is tr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Head
A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may not have a head, but many bilaterally symmetric forms do, regardless of size. Heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nervous tissue concentrate at the anterior region, forming structures responsible for information processing. Through biological evolution, sense organs and feeding structures also concentrate into the anterior region; these collectively form the head. Human head The human head is an anatomical unit that consists of the Human skull, skull, hyoid bone and cervical vertebrae. The term "skull" collectively denotes the mandible (lower jaw bone) and the cranium (upper portion of the skull that houses the brain). Sculptures of human heads are general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toad
Toad is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands. A distinction between frogs and toads is not made in scientific taxonomy, but is common in popular culture (folk taxonomy), in which toads are associated with drier, rougher skin and more terrestrial habitats. List of toad families In scientific taxonomy, toads include the true toads (Bufonidae) and various other terrestrial or warty-skinned frogs. Non-bufonid "toads" can be found in the families: * Bombinatoridae ( fire-bellied toads and jungle toads) * Calyptocephalellidae (helmeted water toad and false toads) * Discoglossidae ( midwife toads) * Myobatrachidae (Australian toadlets) * Pelobatidae (European spadefoot toad) * Rhinophrynidae ( burrowing toads) * Scaphiopodidae (American spadefoot toads) * Microhylidae ( narrowmouth toads) Biology Usually the largest of the bumps on the skin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle English
Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English period. Scholarly opinion varies, but the ''Oxford English Dictionary'' specifies the period when Middle English was spoken as being from 1150 to 1500. This stage of the development of the English language roughly followed the High to the Late Middle Ages. Middle English saw significant changes to its vocabulary, grammar, pronunciation, and orthography. Writing conventions during the Middle English period varied widely. Examples of writing from this period that have survived show extensive regional variation. The more standardized Old English language became fragmented, localized, and was, for the most part, being improvised. By the end of the period (about 1470) and aided by the invention of the printing press by Johannes Gutenberg in 14 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
