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They have eight-legs, two big fangs, and are pretty hairy, but did you know that some species of tarantula are brightly coloured?

Tarantulas like the Cobalt Blue (Hapolpelma lividum) or the critically endangered Gooty sapphire ornamental (Poecilotheria metallica) have bright blue legs.

In the past, scientists have been curious as to why these nocturnal hunters would need such brightly coloured bodies - especially as scientists thought they were colour-blind.

However, a recent study published in Proceedings of the Royal Society B has challenged these ideas.

Researchers from Yale-NUS College and Carnegie Mellon University think that the tarantula's bright blue colours might be used to attract and communicate with potential mates, instead of scaring away potential predators.

As part of the study researchers looked at the patterns of light-sensitive proteins called opsins, which can be found in animal eyes.

The scientists found that these brightly-coloured night-time tarantulas had lots of opsins, which are usually found in spiders that have colour vision, and are active during the day, like the Peacock spider.

These results show that while they may not be able to see every colour, they can certainly see the bright blue colour of their legs.

One of the scientists, Dr Foley, said: "While the precise function of blueness remains unclear, our results suggest that tarantulas may be able to see these blue displays, so mate choice is a likely potential explanation. We have set an impetus for future projects to include a behavioural element to fully explore these hypotheses, and it is very exciting to consider how further studies will build upon our results,"

The scientists also traced back the tarantula's ancestors, and found that their 110 million-year-old ancestors were also very likely blue.