Occasional visitors

Basking shark Cetorhinus maximus

Basking sharks were once a fairly common sighting from Lundy’s sidelands and cliffs during the summer months. In recent years however, the number of sightings has fallen considerably. These giants of the oceans (the largest fish found in British waters and, worldwide, only second in size to the whale shark Rhincodon typus found in tropical seas) feed on plankton and will search out areas close to the sea’s surface where winds and currents have concentrated drifting planktonic forms. They may grow to 7.5 m in length, although the ones seen around Lundy are usually smaller than this (typically 3-5 m long).

Basking sharks were first recorded by the island’s Warden in the Lundy Field Society’s Annual Report in 1973 (Dymond, 1973), although they would have been known to occur around the island on a regular basis for many years before that. These were just occasional, non-methodical records of sightings by those willing to record what they saw in the Tavern’s sightings’ logbooks on an ad hoc basis.

In recent years, sightings of basking sharks have become fewer and further between. It is uncertain why this decline in sightings should be happening but it appears widespread throughout the south-west of Britain.

Basking sharks are most likely to be seen from boats on the water or from Lundy’s coastal paths on days when the sea state is relatively calm. They swim slowly, with the dorsal fin usually apparent above the sea surface. The tip of the tail and the tip of the snout may also be apparent from time to time. They may be seen singly or in small groups.

If you happen to see a basking shark, please do make a record of where, when, how many and for how long you saw it/them, in the island logbook in the Tavern (if you’re on the island), or on the sightings form here (if you’re not). Such records add to our understanding of the size and constitution of their groupings and of the timings of their appearances.

Further information about other shark species which occur at Lundy can be found here.

Grey triggerfish Balistes capriscus

The original name of this triggerfish was Balistes carolinensis which refers to ‘Carolina’, the collective name of the US east coast states of North and South Carolina. In turn, the name ‘Carolina’ is in homage to King George I of England, as the Latin word for Charles is Carolus. This dip into onomastics is relevant here as the grey triggerfish, which is occasionally encountered at Lundy, has its centre of distribution in this part of the western Atlantic, although it is found from Nova Scotia in the north to Argentina in the south.

The reason why it turns up around the south-west coasts of England and Ireland is that individuals are brought across the Atlantic as a result of the warm water current known as the Gulf Stream. The fish is also known to breed in the Mediterranean. According to the MarLIN website, it was originally considered an uncommon visitor to northern European seas, but an increase in records around the Cornish coast may indicate it is now breeding there. Due to our gradually increasing sea temperatures, it looks like this ‘non-native’ is here to stay.

Sunfish Mola mola

The sunfish is the largest (in terms of its weight) bony fish found in the world’s oceans. It is a most peculiar fish, both in terms of its shape and its behaviour. It is huge (over 3 m long when fully grown and weighing 1.3 tonnes!), flat (it looks like it’s been squashed from side to side) and circular (some say it looks like a dinner plate with two protruding fins). They are often spotted resting on their sides at the surface of the sea, supposedly basking in the sunshine - which is where its common name of sunfish comes from. It has been suggested that this basking behaviour is to help the sunfish raise its body temperature after diving down to cooler waters to feed.

Those seen off Lundy tend to be quite small (up to 1 m long). Look out for their characteristic ‘flapping’ at the surface as they switch sides for their sunbathing.

Atlantic bluefin tuna Thunnus thynnus

Bluefin are the largest tunas, measuring over 2 m in length and weighing over 600 kg, and can live up to 40 years. The Atlantic bluefin is native to both the eastern and western Atlantic, though most catches of this species are taken in the Mediterranean Sea.

Bluefin tuna populations have declined severely from overfishing and illegal fishing over the past few decades. The fish is highly migratory and over the past decade they have reappeared in the seas around the British Isles, particularly around the SW peninsula, having been absent for the previous 60 years.

Since 2015, individual bluefin tuna have occasionally been seen off Lundy during the summer months. They are fast swimmers (reaching speeds up to 40 mph!) and are most conspicuous when leaping out of the water.

Portuguese Man o’ War Physalia physalis

Whilst resembling a jellyfish, closer inspection of this strange floating form (correctly termed a siphonophore) will reveal some distinct differences. The ‘sail’ is the most noticeable. This gas-filled structure is called a pneumatophore, its job being to keep the organism afloat and drifting in the ocean’s currents. The rest of the organism is made up of smaller units called zooids, each with a separate function. These can include hunting, digestion and reproduction, yet all operate together to form a colonial organism. The cells forming the tentacles are capable of shooting out stings which may be fatal to humans – so do not touch these tentacles if you come across a washed-up specimen on a beach.

Every now and then Portuguese man o’ war will be washed up onto the Landing Beach at Lundy, having been blown ashore by strong winds.

By-the-wind sailor Velella velella

Like the Portuguese man o’ war, this is another member of the neuston (animals which live partly in and on the sea’s surface). It’s a hydrozoan, about 7 cm long and relies on the wind catching its sail to move it over the water surface. Very small tentacles emerge from the underside of the organism, packed with stinging cells which can paralyse and capture minute planktonic forms, but are harmless to human palms.

By-the-wind sailors may appear washed up on beaches in their hundreds, all being driven on to the shore by the force and direction of the wind. They may occur at Lundy (or on any western-facing shoreline around the British Isles) at any time, though particularly after storms.

Assorted jellyfishes

Although they have the ability to maintain their position in the water column, jellyfishes are weak swimmers and will tend to drift with the ocean currents, often being blown into the Bristol Channel after strong south-westerly winds. Below is an assortment of jellyfish which are most likely to be encountered at Lundy.