Arteries leaving the gills the efferent branchial arteries carry blood rich in oxygen and low in wastes.
Depending on the type of fish, these paired fins are used to stabilise the fish when swimming and also for braking. They range in number from three in a type of scorpionfish Setarches to thousands in the tunas family Scombridae. Fishes which eat large prey such as other fishes and molluscs have short, widely spaced gill rakers. Back to top. Those of individuals that have just given birth tend to be shrunken and darker coloured.
The fish were given to the students with instructions on the techniques necessary for a successful dissection. The fish becomes negatively buoyant and will tend to sink.
Fish Dissection - Cut posterior end of gut. The other organs have been removed to expose the swim bladder at the top of the body cavity. Fish Internal Organs.
A fish swimming in the water expends less energy if it is neutrally buoyant that is, it neither sinks nor floats. Just like the lungs of humans, the gills of fishes are the sites where oxygen is absorbed and carbon dioxide is removed.
The gut and other organs attached to it are pulled forward out of the way, or removed entirely.
Sharks for example do not have a swim bladder, and many species such as the Greynurse Shark , use a different strategy which includes having a large oily liver and specialised body shape to maintain buoyancy. Most fishes have gill arches. Venous blood enters the sinus venosus a thin walled sac then flows into the atrium, followed by the ventricle a thick walled pump.
Marine fishes drink water and excrete only a small volume of very concetrated urine. The hagfishes and lampreys have a single ovary or testis. Search website Submit Search.
Fishes which eat smaller prey have longer, thinner and more numerous gill rakers. The dissection of a Blue Mackerel, Scomber australasicus. The circulatory system in fishes is a single circuit, with blood flowing from the heart to the gills and then to the rest of the body.