Observations of gut contents of leptocephali in the North Equatorial Current and Tomini Bay, Indonesia

Abstract

Visible objects in the gut contents of 13 leptocephali of 11 species and 8 families of eels were observed using photo- graphs of daytime-caught larvae in two different types of marine habitats: the open ocean (North Equatorial Current) and a semi-enclosed deep-water bay (Tomini Bay of Sulawesi Island, Indonesia). Zooplankton fecal pellets of at least 3 shapes, trans- parent oval objects, and one apparent appendicularian were observed to have been ingested. These types of objects are consis- tent with the hypothesis that leptocephali consume marine snow and discarded appendicularian houses, which both typically contain fecal pellets. Appendicularians have not been previously reported to be consumed by leptocephali, but the apparent presence of one in a muraenid intestine suggests that they may occasionally be consumed along with their houses. Chlopsid lep- tocephali in both regions were observed to have consumed large amounts of food material, which indicated that their short in- testines are able to expand more than previously known. Due to net avoidance, most leptocephali are collected at night when feeding may be reduced, so visible food materials are rarely observed in their intestines at night. These photographs show some marine snow-related objects that are consumed by leptocephali more clearly than previous reports.