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How many dorsal spines can a stickleback have?

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Lined seahorse (Hippocampus erectus) — gasterosteiform Lined seahorse (*Hippocampus erectus*).

Sticklebacks, which belong to the family Gasterosteidae within the order Gasterosteiformes, are characterized by a row of 2 to 16 spines located on their backs, positioned in front of a soft-rayed dorsal fin.1

The number of these dorsal spines varies depending on the specific species of stickleback. For example, the three-spined stickleback (Gasterosteus aculeatus) possesses three dorsal spines, while the sea stickleback (Spinachia spinachia) is known as the 15-spined stickleback.1