Dogfish sharks (Squalidae)

This order represents the second largest order and includes 7 families and about 113 species and their most distinguishing feature is the lack of an anal fin. Most species also have a spine in front of the first dorsal fin. The majority are deep water species, and some have luminescent organs. Certain species can reach large sizes for instance the greenland shark, Somniosus microcephalus, with 7 m. Scientists assume that the most abundant species of all known sharks may be the spiny dogfish, (Squalus acanthias), the main species used for "fish & chips".

The dogfishes include a great variety of small to very big sharks. Their biggest variety is in the deep water forms. While most dogfishes possess spines in front of their dorsal fins, some lack them and therefore have been put into different families in earlier years. However, all dogfishes lack an anal fin, a characteristics that is only shared by angel sharks, saw sharks and rough sharks. Dogfishes have a wide geographic and bathymetric range and are found in shallow and deep waters of all oceans. All members of this family show a ovoviviparous style of reproduction (aplacental viviparity). This family consists of 17 genera, including 65 to 70 species.

Sawsharks (Pristiophoridae)

Saw sharks (9 species) are a very unusual group that is often confused with sawfishes, which are rays. The most obvious difference between the two is that saw sharks possess barbels and the teeth, located on the prolonged snout, are different sizes. Only five species are known. One species, the Sixgil Sawshark (Pliotrema warrani), possesses 6 gill slits and lives on the south-eastern Cape Coast of South Africa.
Not much is known about the general biology of this order.

Saw sharks are a very unusual group of sharks with a very long flat snout and lateral sawteeth. The snout resembles a saw with ventral barbels. Saw sharks are often confused with saw fishes, which are rays. Most obvious differences between these two groups are that rays lack barbels, and have their gill slits on the ventral side. Furthermore, saw sharks are of smaller size, compared to saw fishes. The biology of saw sharks is poorly known. Except for the Bahamas sawshark, Pristiophorus schroederi, all of them live on the southern hemisphere. All prefer deeper water and show an aplacental viviparous style of reproduction (ovoviviparity). Of the only 5 species known, one of them, Pliotrema warreni, possesses 6 pairs of gill slits.

Angelsharks (Squatinidae)

Like saw sharks, angel sharks are also often misidentified as rays. The most obvious difference is that angel sharks possess pectoral fins that are not attached to or connected with the head. Angel sharks also possess an enlarged caudal lower lobe but, like dogfishes, do not possess anal fins.
This order includes 18 species, most of them of small size. An exception is the japanese angel shark, Squatina japonica, that reaches 2 m.
Unique in angel sharks is that the lower lobe of the tail is longer than the upper lobe.
Angel sharks spend most of the day buried in sand ranging from very shallow water to 1300 m.

Angelsharks are very unique looking. Their body is very flat and bizarre-shaped. Compared to the similar looking batoids (rays) their pectoral fins are not connected to their heads. The lower lobe of the caudal fin is longer than the upper one. Angel sharks lack an anal fin. They show a wide distribution in temperate and tropical waters from close inshore to the upper continental slopes down to more than 1300m. Except for the Japanese angelshark, Squatina japonica, which reaches 2m, are all others of smaller size. Angel sharks have an ovoviviparous style of reproduction (aplacental viviparoity). All 13 species belong to the same genus.