Fish Phys. REPRODUCTION

chorion

membrane that surrounds the embryo

dichromatism

sexes exhibit different coloration

germinal epithelium

a cluster of multiple spermatocysts bound together with a membrane

gonochoristic

sex (M or F) is fixed and does not change over the natural lifespan

hermaphroditism

• protoandrous — all individuals born male, some become female

• protogynous — all individuals born female, some become male

• simultaneous

heterogametic

one sex has two different sex chromosomes (ie. XY males)

hormone

an internal secretion produced by ductless glands and transported by the circulatory system to other parts of the body, where they regulate the function of target organs and tissues

intromittant organs

external male reproductive structures

• claspers

• gonopodium

iteroparous

species that spawns more than once per lifetime

labile period

period after birth or hatching in which the sex can be manipulated

mesentery

a fold of the membrane lining the body cavity

oocyte

egg cell contained within a follicle

oogenesis

formation and development of eggs

ovipositor

extension of the female genital opening used to deposit eggs

ovulation

discharge eggs from the ovary

pheromone

a hormone secreted into the environment

polygenic

no distinct sex chromosomes, many genes contribute to sex

reproductive strategies (____-parous)

• oviparous — lays external eggs, most fish

• viviparous — young develop internally with no yolk (direct connection to mother)

• ovoviviparous — young develop internally with yolk sac (no direct connection to mother

saltational theory

as fish grow, they change gradually, but have sudden rapid transitions between stages

• rapid transition = exploit a new habitat

• reduces competition between conspecific fish in different stages

semelparous

species that spawns just once per lifetime

sexual dimorphism

differences between females and males

spermatogenesis

formation and development of spermatozoa (ie. sperm)

spermatocyst

functional unit of the testis, where sperm are produced

spermiogenesis

final maturation of spermatozoa

tubercules

raised bumps on the head, body, and fins of male fish

vitellogen

protein from which yolk is derived

vitellogenesis

formation of the yolk of an egg