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Hydra oligactis, also known as the brown hydra, is a species of hydra found widely dispersed in the northern temperate zone. It is a common organism found in still waters from early Spring to late Autumn. It is commonly found attached to the stems of water plants, the undersides of leaves, submerged twigs and on the surface of stones. When ...
Hydra generally react in the same way regardless of the direction of the stimulus, and this may be due to the simplicity of the nerve nets. Hydra are generally sedentary or sessile, but do occasionally move quite readily, especially when hunting. They have two distinct methods for moving – 'looping' and 'somersaulting'.
Hydra oligactis. This species can reproduce in three ways: sexual reproduction, budding, and indirectly through regeneration. [11] When hydra reproduce sexually, simple testes, ovaries, or both will develop on the bodies of an individual. Sperm released into the environment by the testes enters the egg within the ovary.
Fishes are a paraphyletic group and for this reason, the class Pisces seen in older reference works is no longer used in formal taxonomy.Traditional classification divides fish into three extant classes (Agnatha, Chondrichthyes, and Osteichthyes), and with extinct forms sometimes classified within those groups, sometimes as their own classes: [1]
Corydoras acutus; Corydoras adolfoi; Corydoras aeneus [2]; Corydoras agassizii; Corydoras ambiacus; Corydoras atropersonatus; Corydoras axelrodi; Corydoras barbatus
Actinopterygii (/ ˌ æ k t ɪ n ɒ p t ə ˈ r ɪ dʒ i aɪ /; from Ancient Greek ἀκτίς (aktis) 'having rays' and πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish [2] that comprise over 50% of living vertebrate species. [3]
When a fish moves, it creates disturbances in the water that could be detected by the lateral line system, potentially interfering with the detection of other biologically relevant signals. To prevent this, an efferent signal is sent to the hair cell upon motor action, resulting in inhibition which counteracts the excitation resulting from ...
Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key". In modern fishes, the cleithrum is a large bone that extends upwards from the base of the pectoral fin and anchors to the cranium above the gills , forming the posterior edge of the gill chamber . [ 2 ]