Sand Eel Larva
Ammodytes sp.
Type: pelagic, saltwater
Physical Characteristics
Elongated, slender, eel-like body. Translucent or transparent during larval stage with a series of distinct dark pigment spots along the dorsal or ventral midline. Large black eyes and long dorsal and anal fins.
Habitat & Distribution
Coastal marine waters, often found in the plankton layer as larvae before settling into sandy seabed environments in the North Atlantic and North Pacific.
Size & Weight
Larvae range from 4 to 20 mm; adults reach up to 15-30 cm depending on the species.
Similar Looking Species
Larval herrings or sardines; distinguished by the sand eel's more elongated body and specific melanophore (pigment) patterns along the spine.
Ecological Role
Primary forage fish; a critical link in the food web connecting plankton to higher predators like seabirds, whales, and larger fish species.
Diet
Larvae are suction feeders targeting zooplankton, copepods, and invertebrate eggs.
Behavior
Pelagic and planktonic as larvae; as adults, they display burrowing behavior in sandy substrates and gather in large schools.
Reproduction
Synchronous spawning typically in winter; eggs are demersal and stick to sand grains until hatching into the planktonic larvae seen here.
Conservation Status
Least Concern to Data Deficient depending on specific species, though local populations are highly sensitive to overfishing and climate change.
Identification Tips
Look for the extremely thin, straight body, the position of the dark spots along the gut and tail, and the lack of a distinct pelvic fin.
Interesting Facts
Despite their name, they are not true eels. They lack swim bladders and must swim constantly or burrow to maintain their position.
Identified on: 5/20/2026
Mode: Standard