Dogfish is the name for a few small sharks of several different families. They’re best known for the spiny dogfish, that belongs to the Squalidae family, and the smooth dogfish, that belongs to the Triakidae family. Take a look below for 23 more bizarre and weird facts about dogfish.

1. Spiny dogfish have two spines, one in front of each dorsal fin. Surprisingly, they lack an anal fin.

2. They’re found in most oceans around the world, particularly in shallow, temperate waters.

3. Female dogfish grow to lengths of 4 feet, or 120 centimeters, and weigh around 15 to 20 pounds, or 6.3 to 9 kilograms. The males are a bit smaller.

4. Their spines have venom that causes serious damage to whoever comes in contact.

5. They migrate seasonally, preferring to stay in warmer waters.

6. Dogfish feed on a variety of fishes and invertebrates. They’re known for causing massive damage to locally valuable fish.

7. Other species of the spiny dogfish are found in deep waters.

8. The smooth dogfish, Mustelus canis, is found on the Atlantic coast of North America, from Brazil to Cape Cod.

9. The smooth dogfish is grey in color and grows to lengths of about 5 feet, or 150 centimeters.

10. Their population numbers remain steady because they have no commercial value for humans. They also migrate seasonally and feed on smaller fish and invertebrates.

11. The smooth dogfish family includes two small sharks that are abundant on the Pacific coast of the United States. The first is the brown smoothhound, Rhinotriacis henlei, and the second is the leopard shark, Triakis semifasciata.

12. The spiny dogfish are fished for food in Europe, the United States, Canada, New Zealand and Chile. Their meat is primarily ate in England, France, The Benelux countries and Germany.

13. Their fins and tails are processed into fin needles and are use in less expensive versions of shark fin soup.

14. In England, spiny dogfish are sold in fish and chips shops as “huss.” It used to be passed as “rock salmon,” until the government outlawed it by consumer legislation.

15. In France, spiny dogfish was sold as “small salmon,” and in Belgium and Germany it was sold as “sea eel.”

16. They’re also used as fertilizer, liver oil, and pet food.

17. The spiny dogfish was one the most abundant shark species but have no declined significantly, due largely to commercial fishing.

18. They’re classified in the IUCN Red List of threatened species as Vulnerable globally and critically endangered in the Northeast Atlantic. This means that their population in Europe has decreased by around 95%.

19. Recently, the market for spiny dogfish in Europe has increased significantly, which has led to the overfishing and the decline of the species.

20. The reproduction of spiny dogfish is aplacental viviparous, which was previously known as ovoviviparity.

21. Male spiny dogfish insert one clasper into the female oviduct orifice and injects sperm along a groove on the claspers dorsal section.

22. After fertilization takes place, the eggs are surrounded by thin shells called “candles” with one candle usually surrounding several eggs.

23. Mating usually takes place in the winter, with the pregnancy lasting 22 to 24 months.