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Other wildlife

Pen Llŷn a’r Sarnau SAC supports a huge variety and wealth of wildlife. As well as the 9 habitats and 3 species that the SAC was specifically designated to protect, it is also home to thousands of other species ranging from seabirds to basking sharks. Below are just a few examples of some of the interesting finds from Pen Llyn a’r Sarnau SAC!

The largest turtle in the world – tropical visitors

Pen Llŷn a’r Sarnau has quite a history with some unique animals, one of these being the leatherback turtle. In 1988 the largest recorded leatherback turtle in world washed up dead in Harlech, North Wales, measuring nearly 3m and weighting in at 916kg. Turtles may not be an obvious part of Wales’ wildlife, but Pen Llŷn a’r Sarnau is in fact a very important area for this particular species. During the summer months large barrel jellyfish (Rhizostoma pulmo) accumulate in Tremadog Bay attracting leatherback turtles that have made an immense journey here from the tropics following the Gulf Stream. They feed primarily on jellyfish that are composed of more than 95% water – scientists are still trying to understand how they survive on food with such low concentrations of nutrients.

Colour competition between the sexes

Pen Llŷn a’r Sarnau is also home to one of the most colourful fish in the UK, the cuckoo wrasse (Labrus bimaculatus). Only the male is fortunate enough to have the elaborate blue and orange colouration, the female being orange with three black dots on her back. But females come first – all the fish are born as female with the dominant female in a group turning into a male.

Small but significant

Below the sea’s surface thousands of tiny creatures can be found hiding in crevices and under sediment throughout the SAC. Sometimes these live in huge abundance. Studies have shown that an area the size of an A4 piece of paper in some parts of Tremadog Bay is home to over a thousand animals and over 80 species. The sediment is literally alive with animals!

Mud runner crab Sand mason


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