Glass eel is a term used to describe juvenile eels that have just arrived at their freshwater habitats after migrating from the ocean. The spelling of this term is simple, with its pronunciation and spelling quite closely related. The word begins with the voiced velar fricative sound /g/, followed by the long vowel sound /æ/. The second part "eel" is pronounced with the long vowel /iː/. The spelling of the term incorporates the final consonant cluster /sl/, denoted by the letters "ss".
Glass eel refers to a developmental stage of eel larvae that exhibit a transparent, glass-like appearance. It is a crucial life stage in the life cycle of various eel species, particularly the anguillid eels, such as the European eel (Anguilla anguilla) and American eel (Anguilla rostrata).
At this stage, glass eels are typically small, slim, and semi-transparent, measuring only a few centimeters in length. They possess a slender, elongated body with a pointed snout and a pair of small, undeveloped pectoral fins. Their lack of pigmentation creates a glassy appearance, allowing one to observe their internal organs.
Glass eels are renowned for their migratory behavior, in which they undertake long-distance journeys from their hatching grounds in the ocean to freshwater rivers and estuaries, where they will mature and grow into adult eels. This journey is also known as the "eel migration." The remarkable capability of glass eels to navigate and conquer various obstacles during their migration is still not fully understood and continues to fascinate scientists.
Due to their economic and ecological importance, glass eels are heavily targeted for commercial purposes, particularly in East Asia and Europe, where they are considered a culinary delicacy. Consequently, the glass eel population has significantly declined in recent years, leading to conservation concerns and the implementation of regulations to protect them.
The word glass eel has a straightforward etymology. The term glass refers to the translucent appearance of young eels when they are in their larval stage. They appear almost transparent and have a glass-like appearance, hence the name glass eel.