Forest floors reveal overlooked seed dispersers: Slugs, beetles and crabs spread viable seeds

A recent review led by The University of Hong Kong has uncovered a previously overlooked player in seed dispersal: small invertebrates including slugs, beetles, crickets and crabs. Traditionally, scientists have focused on birds and mammals as the primary agents of seed dispersal over long distances. However, this new synthesis of global evidence reveals that these tiny ground-dwelling creatures also play a crucial role, particularly in forest regeneration and biodiversity conservation.

Invertebrate-mediated seed dispersal, known as invertebrate endozoochory, involves seeds passing through an animal's digestive tract and remaining viable when deposited. The review, published in Trends in Plant Science, consolidated data from 43 peer-reviewed studies, demonstrating that at least 51 invertebrate species from Oceania, Asia, Europe, and North America have been observed dispersing viable seeds.

For instance, a freshwater crab in Japan can ingest over a thousand seeds in one night and deposit them in underground burrows, protecting them from predators and harsh conditions. This "invertebrate endozoochory syndrome" refers to plants that have evolved traits specifically suited to these small dispersers, such as producing small, resilient seeds and fruits at ground level.

Although seeds may travel shorter distances than transported by birds or mammals, this localized dispersal can still benefit plant regeneration by reducing competition near the parent plant and placing seeds in optimal microhabitats. Researcher Professor Si-Chong Chen emphasized that invertebrates are often overlooked due to size bias, yet their cumulative contribution to ecosystems can be substantial.

Conservation efforts may benefit from considering invertebrates, as many plant species rely on animal-mediated dispersal, and the decline of large mammals and birds due to habitat loss may reduce opportunities for regeneration. The findings suggest that future studies should examine the frequency and impact of invertebrate-mediated seed dispersal across different habitats and integrate these findings into conservation planning.