Ichthyology Lecture 14 - Fish Reproduction

What kind of development is on the first slide

Rainbow trout

Describe the female reproductive organ in fish

Ovaries; paired, can be up to 30-70% of their weight during reproductive periods

What is true about female fish

Many lack sexual dimorphism and dichromatism

Describe the male reproductive organ in fish

Testes; up to 12% of body weight during reproductive periods

Milt

Sperm; exits through abdominal pore

Where do chondrichtheyes store sperm

Seminal vesicle

Where do teleosts store sperm

Sperm duct

Intermittent organ

Modified fin; claspers or ovipositors

What is an example of fish with sexual dimorphism

Stoplight parrotfish and male eastern creek chubsuckers

Describe the sexual dimorphism traits of chubsuckers

3 tubercles on both sides of head, made of keratin, shed after breeding season

What are the 4 stages of development

Cleavage, blastula, epiboly, gastrula

Cleavage

Early cell division

Blastula

Hollow ball of eggs

Epiboly

Spreading and thinning of ectoderm

Gastrula

Formation of the gut

R-selection

Selective strategy that favors production of many offspring, short life span, little care

What is an example of r-selection species

Danios scatter eggs and provide no parental care

K-selection

Favors few offspring, long life span, long term parental care

Example of K-selection species

Bonethead sharks; pups born alive, few offspring, extended parental care

What are the five major stages of development

Embryonic, larval, juvenile, adult, senescent

Saltational theory

Development proceeds gradually until an abrupt change in behavior

What is an example of saltational theory

Ability of larva to catch food

Alternative theory

Entire process of development is gradual and stages are arbitrary

Embryonic period

Developing individual is entirely dependent on nutrition