Page 66 - Invasive_Species_2013

Mediterranean invasive species factsheet

MOLLUSCS

Reproduction Common name: Ragged sea hare

Characteristic branching
papillae on body
identification

Scientific Name:
Bursatella leachii
Picture Stolon

Key identifying features
Brief history
This large sea slug can reach more than 10 cm in
length. The body has numerous long, branching, Bright blue eye-spots
white papillae (finger-like outgrowths) that give the
animal its ragged appearance. A key distinctive
feature is its grey-brown body with dark brown
blotches on the white papillae and bright blue eye-
spots scattered over the body. The head bears four
tentacles: two olfactory tentacles originating on the Reproduction
dorsal part of the head resembling long ears, and two Bursatella leachii is a hermaphroditic species with a
oral tentacles, similar in shape, near the mouth. very fast life cycle and continuous reproduction.
Adults lack an external shell. When mating, one individual acts as a male and
crawls onto another one to fertilize it. A large mass of
Field identification signs and habitat tangled strings of purple eggs is produced and the
larvae develop within 20 days. Sexually mature sea
This species occurs most commonly in shallow,
hares appear after 2–3 months.
sheltered waters, often on sandy or muddy bottoms
with Caulerpa prolifera, well camouflaged in seagrass
beds, and occasionally in harbour environments. If
disturbed or touched it can release purple ink.

Its behaviour varies with the time of day, as it is more
active during the daytime and hides at night. In the
early morning sea hares are found clustered together
in groups of 8–12 individuals, and they disperse to
feed on algal films during the day. They reassemble
again at night.

Bursatella leachii. Photo: D. Poloniato- WWF-MPA Miramare

Bursatella leachii. Photo: B. Weitzmann Bursatella leachii. Photo: B. Weitzmann

Monitoring Marine Invasive Species in Mediterranean MPAs: A strategy and practical guide for managers 63