FuzzyBot: Importing a new version from external source

2025-08-28T03:54:57Z

Importing a new version from external source

New page

Fish have small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal. However, some fish have relatively large brains, notably [[Mormyridae|mormyrids]] and [[shark]]s, which have brains about as large for their body weight as birds and [[marsupial]]s. At the front of the brain are the [[olfactory bulb|olfactory lobes]], a pair of structures that receive and process signals from the [[nostril]]s via the two [[olfactory nerve]]s. Fish that hunt primarily by smell, such as hagfish and sharks, have very large olfactory lobes. Behind these is the [[telencephalon]], which in fish deals mostly with olfaction. Together these structures form the forebrain. Connecting the forebrain to the midbrain is the [[diencephalon]]; it works with [[hormone]]s and [[homeostasis]]. The [[pineal body]] is just above the diencephalon; it detects light, maintains [[circadian]] rhythms, and controls color changes. The [[midbrain]] contains the two [[Midbrain#Corpora quadrigemina|optic lobes]]. These are very large in species that hunt by sight, such as [[rainbow trout]] and [[cichlid]]s. The [[metencephalon|hindbrain]] controls swimming and balance.The single-lobed cerebellum is the biggest part of the brain; it is small in hagfish and [[lamprey]]s, but very large in [[mormyrid]]s, processing their [[electric fish|electrical sense]]. The brain stem or [[myelencephalon]] controls some muscles and body organs, and governs respiration and [[osmoregulation]].

Translations:Fish/59/en - Revision history

FuzzyBot: Importing a new version from external source