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The heart pumps the blood in a single loop throughout the body. In most fish, the heart consists of four parts, including two chambers and an entrance and exit. [ 20 ] The first part is the sinus venosus , a thin-walled sac that collects blood from the fish's veins before allowing it to flow to the second part, the atrium , which is a large ...
The primitive jawless fish have only a single testis located in the midline of the body, although even this forms from the fusion of paired structures in the embryo. [ 41 ] Under a tough membranous shell, the tunica albuginea , the testis of some teleost fish, contains very fine coiled tubes called seminiferous tubules .
Catfish (or catfishes; order Siluriformes / s ɪ ˈ lj ʊər ɪ f ɔːr m iː z / or Nematognathi) are a diverse group of ray-finned fish.Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, the Mekong giant catfish from Southeast Asia, the wels catfish of Eurasia, and the piraíba of South America, to ...
The primitive jawless fish have only a single testis, located in the midline of the body, although even this forms from the fusion of paired structures in the embryo. [2] Under a tough membranous shell, the tunica albuginea, the testis of some teleost fish, contains very fine coiled tubes called seminiferous tubules.
A lymph heart is an organ which pumps lymph in lungfishes, amphibians, reptiles, and flightless birds back into the circulatory system. [ 1 ] [ 2 ] In some amphibian species, lymph hearts are in pairs, and may number as many as 200 in one animal the size of a worm , while newts and salamanders have as many as 16 to 23 pairs of lymph hearts.
Clariid catfish are characterized by an elongated body, the presence of four barbels, long dorsal and anal fins, and especially by the autapomorphic presence of a suprabranchial organ, formed by tree-like structures from the second and fourth gill arches.
[6] [8] The fins are otherwise brown, though the body's mottling may extend into the fins. The anal fin has 14 to 17 rays and a round margin. [8] The flathead catfish grows to a length of 155 cm (61 in) [8] and may weigh up to 55.79 kg (123.0 lb), [9] making it the second-largest North American catfish (after the blue catfish, Ictalurus ...
Branchial hearts are accessory pumps that supplement the action of the systemic heart in a cephalopod's body. They are myogenic in nature. [1] Branchial hearts are always in pairs located at the base of the gills. Each branchial heart consists of a single chamber. [1] [2] They pump blood through the gills via the afferent branchial veins.