larval fish, pelagic, saltwater
Eel Leptocephalus Larvae
Anguilla sp. (larval stage)
Transparent, leaf-shaped (laterally compressed) bodies with a jelly-like consistency. They possess a small head, long digestive tract, and visible muscular segments called myomeres. The body is thin and ribbon-like, lacking pigments except in the eyes.
- Habitat
- Found in upper layers of the open ocean (epipelagic zone…
- Size & weight
- Length typically ranges from 5 mm to 10 cm depending on…
- Diet
- Primarily feed on marine snow (organic particles, discar…
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Physical characteristics
Transparent, leaf-shaped (laterally compressed) bodies with a jelly-like consistency. They possess a small head, long digestive tract, and visible muscular segments called myomeres. The body is thin and ribbon-like, lacking pigments except in the eyes.
Habitat & distribution
Found in upper layers of the open ocean (epipelagic zone) during migration from spawning grounds towards continental shelves. Geographically widely distributed across the Atlantic, Pacific, and Indian Oceans.
Behavior
Drift with ocean currents (planktonic). They exhibit diel vertical migration, staying deeper during the day to avoid predators and rising at night.
Diet
Primarily feed on marine snow (organic particles, discarded appendicularian houses, and fecal pellets) and small gelatinous zooplankton. They do not consume typical zooplankton like copepods.
Reproduction
This is a temporary life stage. Adult eels spawn in deep ocean waters; the eggs hatch into leptocephali which drift for months to years before metamorphosing into glass eels upon reaching coastal waters.
Ecological role
Leptocephali serve as a significant link in the marine food web, consuming marine snow and being preyed upon by various marine predators. They transport nutrients from remote spawning areas to coastal regions.
Similar species
Conger eel larvae and Tarpon larvae (Megalops). They are distinguished by the specific count and shape of myomeres (muscle segments) and the positioning of the dorsal fin relative to the anal fin.
Identification tips
Look for a transparent, willow-leaf body shape and large black eyes. The presence of distinct v-shaped muscle segments (myomeres) along the body is a definitive identifier for elopomorph fish larvae.
Interesting facts
The term 'leptocephalus' literally means 'slim head'. For a long time, these larvae were thought to be a separate genus of fish because they look nothing like the adult eels they eventually become.