Invertebrates Animal sexual behaviour

courting garden snails – 1 on left has fired love dart 1 on right.



a male star coral releases sperm water.

invertebrates hermaphrodites. hermaphroditic land snails begin mating elaborate tactile courting ritual. 2 snails circle around each other 6 hours, touching tentacles, , biting lips , area of genital pore, shows preliminary signs of eversion of penis. snails approach mating, hydraulic pressure builds in blood sinus surrounding organ housing sharpened dart. dart made of calcium carbonate or chitin, , called love dart. each snail manoeuvres genital pore in best position, close other snail s body. then, when body of 1 snail touches other snail s genital pore, triggers firing of love dart. after snails have fired darts, copulate , exchange sperm separate part of mating progression. love darts covered mucus contains hormone-like substance facilitates survival of sperm.

penis fencing mating behaviour engaged in species of flatworm, such pseudobiceros bedfordi. species engage in practice hermaphroditic, possessing both eggs , sperm-producing testes. species fence using two-headed dagger-like penises pointed, , white in colour. 1 organism inseminates other. sperm absorbed through pores in skin, causing fertilisation.

corals can both gonochoristic (unisexual) , hermaphroditic, each of can reproduce sexually , asexually. reproduction allows corals settle new areas. corals predominantly reproduce sexually. 25% of hermatypic corals (stony corals) form single sex (gonochoristic) colonies, while rest hermaphroditic. 75% of hermatypic corals broadcast spawn releasing gametes – eggs , sperm – water spread offspring. gametes fuse during fertilisation form microscopic larva called planula, typically pink , elliptical in shape. synchronous spawning typical on coral reef , often, when multiple species present, corals spawn on same night. synchrony essential male , female gametes can meet. corals must rely on environmental cues, varying species species, determine proper time release gametes water. cues involve lunar changes, sunset time, , possibly chemical signalling. synchronous spawning may form hybrids , perhaps involved in coral speciation.

butterflies spend time searching mates. when male spots mate, fly closer , release pheromones. performs special courtship dance attract female. if female appreciates dancing may join him. join bodies end end @ abdomens. here, male passes sperm female s egg-laying tube, fertilised sperm.

many animals make plugs of mucus seal female s orifice after mating. such plugs secreted male, block subsequent partners. in spiders female can assist process. spider sex unusual in males transfer sperm female on small limbs called pedipalps. use these pick sperm genitals , insert female s sexual orifice, rather copulating directly. on 14 occasions sexual plug made, female produced without assistance male. on ten of these occasions male s pedipalps seemed stuck while transferring sperm (which case in other species of spider), , had great difficulty freeing himself. in 2 of ten instances, eaten result.