Creature of the Month – Lesser Brown Scorpion

Scorpions are members of the class Arachnida and are closely related to spiders. Its body is divided into three parts ie. head, abdomen and tail. They have four pairs of clawed legs and are easily recognised by a pair of large pedipalps and a segmented tail, often carried in a characteristic forward curve over the back, ending with a venomous stinger. While they sometimes use the sting to paralyse their prey, studies suggest that it is more often used for defense purposes. The venom of some species can be fatal but those found in Singapore are not known to be that dangerous.

Scorpions in Singapore has not been well studied. I am not sure how many species exists in Singapore, probably fewer than 8 species. The Lesser Brown Scorpion (Isometrus maculatus) should be the most common species as I have seen them taken by many night macro photographers. They are medium sized species where the females will reach between 4 to 6.5 cm in bodysize, whereas the males, due to their greatly elongated metasoma, may reach about 9 cm.

(A female spotted scorpion staying motionlessly on a tree truck)

(A female scorpion staying motionlessly on a tree truck)

The Lesser Brown Scorpions are nocturnal creatures. They hunt and feed at night while they rest during the day, hiding beneath loose rocks, loose bark of fallen trees, etc. Hence, not many of us in Singapore have spotted them. I have only seen them during two night macro outings organised by Nature Photographic Society, Singapore. One at Venus Drive a few years ago and yesterday at Zhenghua Forest, both led my our macro master, Allan Lee. Scorpions are known to glow when exposed to ultraviolet light due to the presence of fluorescent chemicals in the cuticle. Our experienced Allan brought along a hand-held UV light which was very useful to search for such nocturnal creatures. We found at 8 of them within a small radius of 10 metres!

(Scorpion in ultraviolet light)

(Scorpion in ultraviolet light)

Like most other scorpions, they go through courtship similar to that of spiders. Their young are born alive and immature scorpions stay on their mother’s back until their first moult. The young will moult into second instar within days on the mother’s back and leave there a few days later.

(A female scorpion carrying  the youngs on its back)

(A female scorpion carrying the young on its back under UV lighting)

Here is a side view shot under normal lighting, where the young scorpions looked big enough and ready to leave their mother.

(Side view under normal light)

(Side view under normal light)

Scorpions eat a variety of insects, spiders, millipedes, lizards and other scorpions. What about centipedes which are equally deadly predators? A quick research over the internet suggests that there is no clear winner when both of them meet. On this occasion, the Scorpion won the fight and got to eat its victim!

(Scorpion eating centipede)

(Scorpion eating centipede)

Here is a YouTube video showing a centipede winning the battle against a deadly scorpion:

Note: All the above images were taken at Zhenghua forest on 31 May 2014.

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