Fish Biology & Physiology Flashcards

Which migratory life history pattern describes fish that hatch in freshwater, migrate to the ocean to grow, then return to freshwater to spawn?

Answer: Anadromy

Anadromy describes the pattern seen in salmon and shad, where fish are born in freshwater streams, migrate to the ocean for growth, and then return to freshwater to reproduce.

What is the primary function of pyloric caecae in bony fishes?

Answer: Increasing absorptive surface area for nutrient uptake

Pyloric caecae are finger-like pouches at the pyloric junction of the stomach and intestine that significantly increase digestive surface area, enhancing the absorption of nutrients from digested food.

What type of scales are exclusively characteristic of cartilaginous fishes such as sharks and rays?

Answer: Placoid scales

Placoid scales (dermal denticles) are tooth-like dermal structures found only in cartilaginous fishes; they are structurally similar to vertebrate teeth and give shark skin its characteristic rough texture.

In ovoviviparous fish reproduction, how does embryo development occur?

Answer: Eggs are retained internally and young are born live, nourished by egg yolk

In ovoviviparity, fertilized eggs are retained inside the mother's body where they develop nourished by yolk reserves, with live young born after internal hatching — as seen in many sharks and rockfish.

What is the role of the oil globule found in the eggs of many pelagic fish species?

Answer: Providing buoyancy and serving as an energy reserve for the embryo

The oil globule in pelagic fish eggs provides positive buoyancy to keep eggs in the water column and serves as a lipid energy reserve that fuels embryonic development and early larval stages.

What physiological transformation does the term 'smoltification' describe in juvenile salmon?

Answer: Transformation from freshwater-adapted parr to seawater-ready smolt

Smoltification is the complex hormonal and physiological transformation that prepares juvenile salmon (parr) for life in seawater, involving changes in gill structure, body coloration, behavior, and osmoregulatory capacity.

Besides their role in hearing and balance, how are fish otoliths used by fisheries scientists?

Answer: To estimate individual fish age using annual growth rings

Otoliths accumulate calcium carbonate in daily and annual increments (annuli), creating growth rings analogous to tree rings that allow fisheries biologists to accurately determine fish age.