Fish Reproduction Reproductive Systems Cartilaginous Fishes Ducts lead

Fish Reproduction

Reproductive Systems • Cartilaginous Fishes – Ducts lead from testes and ovaries to cloaca (common passage for digestive, excretory and reproductive systems) – Cloaca leads to the anus • Bony & Jawless Fishes – Have a urogential opening (separate opening behind the anus for urine and gametes)

Reproductive System – Cartilaginous Fish

Reproductive System – Bony Fish

Hermaphrodites • Some fish are hermaphrodites – Deep water fish – Able to fertilize themselves but usually don’t • Sequential Hermaphroditism (a. k. a. Sex reversal) – individuals begin life as one sex but change into the opposite sex – Controlled by sex hormones; triggered by social cues – Protandry - starts as male and changes to female • Example: Clownfish – Protogyny - starts as female and changes to male • Example: Wrasses

Sequential Hermaphroditism

Reproductive Behavior • Adaptations help individuals get together: – Migrations – Displaying particular colors as sex signals – Courtship behavior • Dances • Postures • Nest building

Mating: Release of Gametes • Cartilaginous fishes: Copulation (internal fertilization) – Claspers used to deliver sperm into female cloaca – Male sharks usually bite and hold female • Bony fish: spawn (external fertilization) – Spawning can occur in pairs or in large groups – Eggs fertilized in the water column drift as plankton – Some species deposit eggs on rocks or grass – Some are laid in nests and are guarded

Environmental factors trigger production of sex hormones: Spawning Daylight • Time of spawning is critical Temperature • Spawning controlled by sex hormones Food • Environmental factors trigger production of sex hormones: –Daylight –Temperature –Food

Early Development of Bony Fish • After a few days of embryo development the eggs hatch into larva (fry) • Larva live as plankton • Larva develops into juvenile • Juvenile develops into an adult

Early Development of Cartilaginous Fishes

Oviparous – Deepsea Cat Shark

Ovoviviparous – Portuguese Shark

Viviparous - Hammerheads

“Low Oxygen in Coastal Waters Impairs Fish Reproduction” Atlantic Croaker

Assignment: • Write a short Essay: – Use evidence from this article to support your statements – Your essay needs to include: • Explain how humans are impacting the Atlantic Croaker. • Discuss the long term effects of the human impacts • Suggest some ways to help the Croakers

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