Gasterosteiformes

Gasterosteiformes is an order of ray-finned fish that includes sticklebacks and their allies. These fish are characterized by a variety of adaptations, with many species possessing prominent spines or bony plates. The name "Gasterosteiformes" itself is derived from Greek words meaning "belly spine form," alluding to the dorsal spines found in many members of the order.

The diversity within Gasterosteiformes is notable. The most well-known group, the sticklebacks (family Gasterosteidae), are small, freshwater or anadromous fish famous for their complex breeding behaviors, including nest building by the males. Other families within the order exhibit different lifestyles and morphologies. For instance, the cornetfishes and shrimpfishes (family Fistulariidae and Solenostomidae, respectively) are elongated, slender fish often found in marine environments, adapted for stealthy predation. The sea horses and pipefishes (family Syngnathidae) are perhaps the most distinctive, with their fused jaws forming a tubular snout and their upright swimming posture, with males carrying the eggs in a pouch.

While some Gasterosteiformes are of minor commercial importance, many are primarily of scientific interest due to their evolutionary relationships and unique adaptations. Their distribution is widespread, with species found in both freshwater and marine habitats across the globe, inhabiting temperate and tropical waters. The study of Gasterosteiformes provides valuable insights into fish evolution, behavior, and ecological interactions.