lecithotrope

Lecithotropy is a developmental mode in which embryos obtain most or all of their nutrition from yolk stored in the egg, rather than feeding after hatching. The term lecithotrope (or lecithotrophic) describes organisms that rely on yolk that was deposited in the egg during oogenesis. Eggs are typically larger and endowed with substantial yolk reserves to sustain embryonic and early larval development through to metamorphosis or settlement.

In lecithotrophic development, the larva often does not feed in the plankton. This can result in shorter or more variable pelagic durations and generally reduced dispersal compared with planktotrophic larvae, which feed on external food sources after fertilization. The reliance on yolk also concentrates maternal investment in a smaller number of larger offspring, influencing life-history strategies such as fecundity and timing of reproduction.

Lecithotropy contrasts with matrotrophy, where nourishment is provided to the developing embryo by the mother during gestation or brooding via placental or analogous structures. Evolutionarily, transitions between lecithotrophy, planktotrophy, and matrotrophy reflect trade-offs between offspring size, number, dispersal, and ecological conditions such as food availability and habitat stability.

Taxonomically, lecithotrophic development occurs across diverse groups, including various invertebrates such as echinoderms and mollusks, and is observed in some fish and other animals. The mode has important implications for population structure, colonization potential, and responses to environmental change.