Solar-Powered Sea Slug (Elysia chlorotica) Breeding Guide

Elysia chlorotica is a hermaphroditic sacoglossan that lays egg strings and hatches as a veliger larva. Its obligate diet of Vaucheria litorea and its kleptoplasty make it a lab-studied specialist, not a home-bred aquarium animal.

Overview

Elysia chlorotica is a green sacoglossan sea slug of the eastern North American coast, ranging from Nova Scotia south to Florida and Texas. Adults typically measure 20-30 mm but can reach 60 mm. It practises kleptoplasty: it punctures algal cell walls with its radula and sucks out the contents, retaining chloroplasts that can survive and function for up to nine or ten months.

Reproductive Mode

Adults are simultaneous hermaphrodites that produce both sperm and eggs at the same time. Rather than self-fertilizing, they cross-mate, and after internal fertilization they lay their fertilized eggs in long strings.

Conditioning

The diet is obligate: E. chlorotica feeds only on the intertidal alga Vaucheria litorea. Both adult conditioning and juvenile survival depend on a living supply of this specific filamentous alga, because the slug must continually replenish stolen chloroplasts to power its photosynthesis.

Spawning and Larval Rearing

After holoblastic spiral cleavage and gastrulation, the embryo hatches as a veliger larva that has a shell and a ciliated velum, feeding on phytoplankton. A juvenile prior to feeding on algae is brown with red pigment spots because it lacks chloroplasts; chloroplast uptake begins immediately after metamorphosis from the veliger stage, only once the slug starts feeding on Vaucheria.

Common Challenges

Captive breeding is impractical for hobbyists. The species lives about one year, requires cool water, and depends entirely on a continuous culture of Vaucheria litorea both to feed adults and to allow newly metamorphosed juveniles to acquire functional chloroplasts. These constraints confine reproduction largely to research settings.