Search results
Results from the WOW.Com Content Network
Amphibians are ectothermic, anamniotic, four-limbed vertebrate animals that constitute the class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all tetrapods excluding the amniotes (tetrapods with an amniotic membrane, such as modern reptiles, birds and mammals).
Parthenogenesis (/ ˌpɑːrθɪnoʊˈdʒɛnɪsɪs, - θɪnə -/; [ 1 ][ 2 ] from the Greek παρθένος, parthénos, 'virgin' + γένεσις, génesis, 'creation' [ 3 ]) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means development ...
Parthenogenesis in amphibians. Parthenogenesis is a form of reproduction where eggs develop without fertilization, resulting in unisexual species. This phenomenon is closely related with reproductive modes such as hybridogenesis, where fertilization occurs, but the paternal DNA is not passed on. Among amphibians, it is seen in numerous frog and ...
This muscle system allows the animal to anchor its hind end in position, and force the head forwards, and then pull the rest of the body up to reach it in waves. In water or very loose mud, caecilians instead swim in an eel-like fashion. [15] Caecilians in the family Typhlonectidae are aquatic, and the largest of their kind. The representatives ...
Suborders. Cryptobranchoidea Salamandroidea. Native distribution of salamanders (in green) Salamanders are a group of amphibians typically characterized by their lizard -like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults.
Tadpole. Common frog (Rana temporaria) tadpole. A tadpole or polliwog (also spelled pollywog) 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 ...
Mammal. A mammal (from Latin mamma 'breast') [1] is a vertebrate animal of the class Mammalia (/ məˈmeɪli.ə /). Mammals are characterized by the presence of milk -producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones.
e. The evolution of mammals has passed through many stages since the first appearance of their synapsid ancestors in the Pennsylvanian sub-period of the late Carboniferous period. By the mid- Triassic, there were many synapsid species that looked like mammals. The lineage leading to today's mammals split up in the Jurassic; synapsids from this ...