Uncommon Mediterranean sea hare filmed swimming in Devon harbour

A Plymouth fisherman has captured outstanding footage of a big sea hare gliding by the waters of the Barbican, providing a uncommon glimpse of an uncommon marine customer swimming freely in one of many metropolis’s busiest waterfront settings.

The encounter passed off outdoors Bar Rakuda on Plymouth’s historic waterfront over the late August Bank Holiday weekend, when native scholar and fisherman Charlie Hill noticed a big darkish creature shifting by the water. The animal, estimated to be round 30cm/1 foot lengthy, seemed to be grazing on algae from the harbour wall earlier than swimming out into open water.

Marine professional’s re-assessment reveals thrilling discovery

Scientists from the Marine Biological Association (MBA) in Plymouth first thought it might be species extra generally seen in UK waters, however it’s now believed that the mysterious marine animal is one hardly ever seen earlier than in British coastal waters and another generally related to the Mediterranean and hotter seas additional south. Sightings right here stay comparatively unusual, making the Devon coastal encounter a big one.

MBA Research Aquarium Manager Alix Harvey stated: “When I first viewed the footage, I thought the animal was Aplysia punctata, a species of sea hare that is relatively common around UK coasts. However, after studying the video more closely, I realised it was actually Aplysia fasciata, also known as the black sea hare. The clues were its impressive size and the distinctive way it used its parapodia, the wing-like flaps along the sides of its body, as it swam through the water. Discovering that it was Aplysia fasciata was really exciting because sightings of this species in UK waters are still relatively uncommon.”

An uncommon customer from hotter seas

At first look, sea hares can seem distinctly unglamorous. Resting on rocks or harbour partitions, they resemble outsized black slugs, with smooth our bodies and few apparent distinguishing options. But in frequent with penguins and seals in being ungainly on land, beneath the floor, the footage reveals a completely completely different animal shifting gracefully by the water.

As the creature swims, broad wing-like flaps (parapodia) gently undulate alongside its physique, propelling it by the water with outstanding grace. The footage is hanging for 2 causes: not solely does it seize a hardly ever noticed swimming show, however it additionally paperwork a species that is still a uncommon sighting in UK shores.

“I love finding out anything I can about what’s living in our seas,” stated Charlie, who works on Plymouth’s Barbican and spends a lot of his spare time fishing. “I’d never seen anything quite like this before, so I thought it was worth sharing.”

The species is native to the Mediterranean Sea and elements of the japanese Atlantic, the place it inhabits hotter coastal environments and grazes on algae. In latest years, nevertheless, marine scientists have noticed a rising variety of species historically related to southern waters showing additional north across the UK. Most notable of those is the unprecedented extended interval of sightings and catches of Common octopus (Octopus vulgaris) off the coasts of Devon and Cornwall since early 2025. Recent reviews point out that octopus have unfold from the place they had been final 12 months and at the moment are being caught on each the south and north coasts of Devon and Cornwall, with extra sightings as far afield as Dorset, East Sussex, and Wales.

While a single sighting can’t by itself be attributed to local weather change, information of warm-water species in British seas have gotten more and more essential indicators of how marine ecosystems are responding to rising ocean temperatures. The look of Aplysia fasciata in Plymouth provides to the broader image of adjusting species distributions and shifting habitats as waters across the UK proceed to heat.

Citizen scientists play key position in monitoring marine species

Charlie’s sighting highlights the very important position members of the general public play in serving to scientists perceive the altering marine surroundings. Observations submitted by fishermen, divers, sailors and coastal communities present beneficial details about species distributions and may alert scientists to uncommon arrivals or rising tendencies.

Marine consultants are encouraging anybody who encounters uncommon wildlife to {photograph} it, notice the situation and depth if potential, and report their sighting to DASSH, the Marine Biological Association’s information consultants, by the iNaturalist app, so specialists can monitor species and the way altering marine habitats are influencing the motion of marine life.

“Every record helps us build a better understanding of how marine species are distributed and whether their ranges may be changing,” provides Alix. “It’s improbable that Charlie took the time to movie the animal and share the footage, permitting us to determine such a outstanding customer to Plymouth’s waterfront.

“For a marine biologist, it’s always a thrill when a second look reveals something rarer than expected, and this black sea hare certainly gave us that moment.”