During my time in the United Arab Emirates (UAE) I was pretty keen to try and find a sand boa. How hard could it be when they leave their perfect sine-wave tracks in the sand? Turns out it’s quite hard. A week before leaving, I was following the tracks of a big, fat sand boa when it converged with the tracks of a gecko. A big disturbance in the sand next to a suspicious looking lump told me that I’d found what I was looking for.
The Arabian sand boa (Eryx jayakari) is native throughout the Arabian peninsula and has a small population in southern Iran. Despite being in the same family as anacondas and boas, they only reach lengths of about 40cm. They spend the day buried deep in the sand before heading to the surface at night to forage. Sand boas hide under the sand, with just their eyes peeking out, and wait for unsuspecting prey before grabbing it with a sideways head flick. The description of this hunting tactic should conjure an image of some terrifying mythical beast. In actual fact, they just look like a sock puppet…
Ladies and gentlemen, the Arabian sand boa (Eryx jayakari)
Arabian sand boas are an outlier in the Boidae family (and even the Eryx genus) due to the fact they lay eggs, rather than giving birth to live young. The evolutionary transitions from oviparity (egg-laying) to viviparity (live-birth) has occurred multiple times in vertebrates, particularly in reptiles. In fact, it has occurred independently more times in squamates (lizards and snakes) than in all other vertebrate groups combined.
Dollo’s Law states that complex traits or adaptations can never be regained once lost, or at least not regained in the same form. Arabian sand boas are one of a handful of examples that seem to be breaking this law, though they don’t quite manage it.