Guest post: Shemaiah Kentish, George Mason University An alevin is a newly hatched salmon or trout that still has its yolk-sac attached. The yolk-sac provides the alevin nourishment for the first 2-3 weeks after hatching. Typically, at this life stage, salmon or trout will stay in the gravel but they might be pushed into open … [Read more…]
Guest post: Shemaiah Kentish, George Mason University The abyssopelagic zone is the region of deep water from 4,000m to the ocean. This is a the deepest part of the pelagic zone other than the hadopelagic deep sea trenches. This region is typically home to chemosynthetic bacteria, tubeworms, and small fish. Occasional residents include sharks, shrimp, and … [Read more…]
An amphidromous fish is a type of diadromous fish which migrates between fresh and saltwater. Unlike anadromous and catadromous fish, which migrate explicitly for the purposes of breeding, amphidromous fish migrate for other purposes. A typical cycle of amphidromy includes eggs hatching in freshwater or estuaries, larvae drifting out into the open ocean to feed … [Read more…]
Guest post: Gretchen Stokes, University of Florida Air-breathing fishes are those that respire using aerial gas exchange instead of, or in addition to, that of the water. Air-breathing is an ancient vertebrate specialization that evolved from aquatic hypoxia (e.g., areas of seasonally flooded wetlands, under ice). Air-breathing fishes are equipped with one or more modified respiratory … [Read more…]
Aquaculture is defined by the Food and Agriculture Organization of the United Nations as the farming of aquatic organisms (e.g., fish, mollusks, crustaceans, plants) and harvest by an owner who is responsible for the maintenance, protection, and enhancement of the cultivated stock. Aquaculture is considered the fastest growing food production sector. In terms of global production, farmed … [Read more…]
Ampullae of Lorenzini are a network of electroreceptors, sensory organs that detect electric fields in water, found in chondrichthyes (sharks, rays, and chimaeras). The ampullae are a series of symmetrical pores, concentrated around the snout and nose, connected by gel-filled canals. They can conduct electrical impulses so small, that chondrichthyes are likely to be more sensitive … [Read more…]
An anadromous fish hatches and spawns in fresh water but spends most of its life in the salt water. This dual life cycle allows the younger fish to grow and feed in the less perilous fresh water habitats (fewer predators in the smaller systems) and the older, larger fish to grow and feed in the marine … [Read more…]
The anal fin is found on the ventral side of fish, often, but not always, at the base of the anus. Along with the dorsal fin, the main purpose of the anal fin is stabilize the fish and keep it from rolling in the water. For knifefish (order Gymnotiformes), which have neither pelvic or dorsal fins, … [Read more…]
The adipose fin is a small fleshy fin found posterior to the dorsal fin and anterior of the caudal fin. It is only found on few fish, including trout, salmon, and catfish. When it was named, it was thought to hold fat, or adipose, tissue. Once this hypothesis was disproved, fisheries biologists long considered this … [Read more…]