Ammodytidae
Ammodytidae is a family of perciform fishes commonly known as sand lances, sand eels, or launce. This family comprises about 20 species distributed worldwide in temperate and cold waters of the Atlantic, Pacific, and Arctic Oceans. They are slender, eel-like fish that inhabit coastal and offshore waters, typically burying themselves in sandy or muddy substrates. Sand lances are important members of marine ecosystems, serving as prey for various larger fish, birds, and marine mammals.
Characteristics
Sand lances are characterized by their elongated, cylindrical bodies, lacking scales, and possessing a single dorsal fin extending almost the entire length of their backs. They have small mouths with numerous, fine teeth, and their bodies are often translucent or slightly pigmented. These fish are typically small, ranging in size from 10 to 40 centimeters (4 to 16 inches). Their lack of scales and streamlined bodies make them well-adapted to burrowing in the sediment, where they spend much of their time.
Environments
Ammodytidae are primarily found in coastal and offshore waters, inhabiting sandy or muddy substrates. They prefer areas with moderate water currents and depths ranging from the intertidal zone to several hundred meters. Sand lances are often found in large schools, which can be a significant food source for predators. They are particularly abundant in the North Atlantic, where they play a crucial role in the food web.
Diet
Sand lances are primarily planktivorous, feeding on a variety of zooplankton, including copepods, krill, and other small crustaceans. They use their small mouths and numerous teeth to filter the water for prey, which they consume in large quantities.
Reproduction
Sand lances reproduce by spawning, releasing large quantities of eggs into the water column. The eggs are pelagic, meaning they drift freely in the water, and hatch into larvae that are initially transparent and planktonic. As they grow, sand lance larvae develop pigmentation and eventually settle onto the bottom, where they adopt a burrowing lifestyle.
Ecological Importance
Sand lances are a key component of the marine ecosystem, serving as a vital food source for various predators. They are preyed upon by commercially important fish species such as cod, pollock, and haddock, as well as by marine mammals like seals and dolphins. They also provide food for seabirds, including puffins, gulls, and terns. The abundance and distribution of sand lances can significantly influence the populations of these predators, making them an important indicator species for assessing the health of marine ecosystems.