Jorunna funebris (Dotted Nudibranch)

IUCN

Scientific Name：Jorunna funebris

Basic Information

Scientific classification

name：Jorunna funebris (Dotted Nudibranch)
Scientific Name：Jorunna funebris
Outline：Mollusca
Family：Discodorididae Jorunna

Vital signs

length：Commonly 4–7 cm; large to ~10 cm
Weight：Not standardized (small dorid nudibranch)
lifetime：Months to ~1–2 years (environment‑dependent)

Feature

White mantle with black rings; dark rhinophores & gills; caryophyllidia on dorsum; sponge‑feeder; hermaphrodite with ribbon eggs.

Distribution and Habitat

Tropical Indo‑Pacific reefs/slopes/lagoons (1–25+ m), sponge‑rich areas.

Appearance

Oval, flattened, rough dorsum; distinctive black rings/spots; dark sensory rhinophores and gill plume.

Details

Jorunna funebris, often called the dotted (Dalmatian) nudibranch, is a dorid sea slug in familyDiscodorididae. The mantle is covered with dense caryophyllidia (spicule‑bearing tubercles) and shows a distinctive white background with black rings/spots. Rhinophores and gill plume are typically dark.

Ecology & Biology

Diet: sponge‑feeding (reports include Haliclona spp. among others); dietary chemicals may confer deterrence.
Behaviour: slow crawler on reef surfaces; secretes mucus and withdraws when disturbed.
Reproduction: a simultaneous hermaphrodite; lateral copulation and deposition of a ribbon‑like egg mass on hard substrates.

Identification

Oval, flattened body with a rough dorsum of caryophyllidia; several to many black rings/spots on a white mantle.Rhinophores and branchial plume are dark brown to black. Spot pattern varies geographically and among individuals.

Size & Longevity

Length: commonly 4–7 cm, occasionally up to ~10 cm.
Life: estimated months to ~1–2 years depending on conditions.

Range & Habitat

Widespread across the tropical Indo‑Pacific from the Indian Ocean and Southeast Asia to the Western Pacific. Typical on reefs, reef slopes and lagoons where sponges are abundant (~1–25+ m).

Roles & Threats

Roles: helps structure sponge communities; a conspicuous subject for macro photography and citizen‑science surveys.
Threats: habitat degradation, marine heatwaves and collection/disturbance.

IUCN: generally treated as Not Evaluated (NE) at global level.

FAQ

Q1. Are the black “rings” diagnostic? Ring number/size varies, but the combination of white mantle + black rings + dark rhinophores/gills is characteristic.

Q2. Is it poisonous? Not actively harmful to humans; may sequester sponge‑derived chemicals—avoid handling.

Q3. How to tell from similar species? Several Jorunna are white‑and‑black; this species shows clear rings and a coarse, caryophyllidia‑studded dorsum.

Q4. When is it most active? Often found in shaded reef zones; night dives increase encounter rates.