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The order Squaliformes is a large, ancient order of sharks. Sharks from this order have two dorsal fins -usually with spines-, no anal fin, and no nictitating membrane on the eyes. Squaliform sharks are extremely variable in size and shape, and can be found in most marine habitats throughout the world.
Heteroptera in its name refers to the difference in size, shape and area of the two dorsal fins. [2] Disparate angelsharks have the typical angel shark body form that is broadly flattened with large pectoral/pelvic fins and eyes and spiracles on the top of their heads. Their common and species name comes from them having dorsal fins of very ...
The pectoral fins are large, but not clearly demarcated from the body, and together with the body are known as the disc. They start from the side of the head in front of the gill openings and end at the caudal peduncle. There are up to two dorsal fins but no anal fin. A slender tail is clearly demarcated from the disc.
Fins allow the sharks to be able to guide and lift themselves. Most sharks have eight fins: a pair of pectoral fins, a pair of pelvic fins, two dorsal fins, an anal fin, and a caudal fin. Pectoral fins are stiff, which enables downward movement, lift, and guidance. The members of the order Hexanchiformes have only a single
Lantern sharks are deepwater fish with light-producing photophores on their bodies. The members of this family are small, under 90 cm (35 in) long, and are found worldwide. [13] Oxynotidae: Rough sharks: 1 5 Rough sharks are characterised by two large dorsal fins, each with a sharp spine, and with the first fin placed far forward above the head.
Close-up of the denticle crest along the dorsal caudal fin margin of the longfin sawtail catshark. The two dorsal fins are similar in size and shape, with blunt apexes. The first dorsal fin originates over the midpoint of the pelvic fin bases, while the second originates over the midpoint of the anal fin base. The pectoral fins are large and ...
The second dorsal fin is slightly smaller than the first but has a longer base. There is a prominent midline ridge along the back, which continues between the dorsal fins. The long, keel-like anal fin originates behind the second dorsal fin. The caudal fin is low and lacks a lower lobe; the upper lobe has a strong ventral notch near the tip ...
Just like all of the Oxynotus species, they have two relatively large dorsal fins that are sail-like, and no anal fin. [5] It has very rough skin and is typically a uniform black to dark grey-brown. Adults generally display darker coloration, often featuring darker blotches on the head and sides, though these blotches can sometimes be ...