Overview
The Sea Bunny (Jorunna parva) is an internet-famous dorid nudibranch celebrated across the globe for its remarkable resemblance to a miniature, fluffy white rabbit. Native to shallow coral reefs and rocky reefs throughout the Indo-Pacific, this tiny marine gastropod possesses two dark, upright ‘bunny ears’ and a feathery ‘tail.’ Far from being mammalian fur, its plush coat is actually a dense covering of specialized sensory papillae that enable it to navigate and taste the underwater world.
Biology and Physical Characteristics
Jorunna parva measures less than an inch in length and exhibits a pale white, yellow, or translucent ochre body covered in microscopic rod-like structures called caryophyllidia. These papillae are capped with dark sensory knobs, creating the appearance of flecked plush fur. The iconic ‘ears’ are actually rhinophores—specialized chemosensory organs packed with chemical receptors that detect food scents and pheromones in ocean currents. At the posterior sits a circular rosette of retractile branchial gills that function like a fluffy tail, extracting oxygen from seawater.
Behavior and Ecology
Despite its gentle, adorable appearance, the Sea Bunny is a specialized carnivore that feeds exclusively on marine sponges. Many of the sponges it consumes contain toxic secondary metabolites; Jorunna parva absorbs these bioactive chemical toxins into its own tissues without harm, rendering its flesh foul-tasting and venomous to passing fish predators. Like most nudibranchs, individuals are simultaneous hermaphrodites, possessing both male and female reproductive organs and exchanging sperm packets when they encounter prospective mates along the reef.
Conservation and Human Impact
Because Jorunna parva is widely distributed across the Indo-Pacific from Japan to eastern Australia, it is not currently threatened with extinction. However, because it depends entirely on delicate coastal reef ecosystems and specific sponge species, coral bleaching, agricultural siltation, and marine heatwaves associated with climate change present indirect environmental challenges to its benthic habitats.
Interesting Factoid
The ‘bunny ears’ of the Sea Bunny are actually acute chemosensory organs called rhinophores that allow the slug to ‘smell’ and ‘taste’ chemicals dissolved in ocean currents to hunt down toxic sponges.
Last updated: October 2026