A future fossil Sometimes, the smallest object can provide more fascination than larger-than-life animal encounters. During a walk over the slippery surface of the dunes, a tiny dark "bead" caught my eye. I bent down to look at it, and saw it was a toktokkie beetle, upended in its typical moisture-collecting pose. On closer inspection, it was apparent that the beetle was stone dead, and totally dessicated. The sand around the head of the beetle had solidified into a solid mass - it looked like the life-saving dew that once dripped down its carapace to sustain it in the scorching desert had been its killer, as it had been dried by the wind into a solid fused mass. One day, millions of years from now, future fossil hunters may stumble across this beetle and marvel at how strange life was back in those days! Posted: Sossusvlei by Phill Steffny, Date: 17 August 2010

4 Comments

Well, that is certainly interesting. It is amazing that they could survive out in the desert anyway.

By: Dana, Date: 17 August 2010

Hey Phill, Your facts are rather off. At Sossusvlei Desert Lodge you are very far from the fog-basking beetles, none of the species on the reserve are know to fog-bask at all. It is not a droplet of water that killed the beetle. Often these beetles are killed by lizards, but they will destroy the whole body. I think this way, where they die with only head damage is from scorpions. It is actually rather common to see in the dunes. The stuff that solidified the sand is actually the moisture from it's guts. Scorpions don't go for the backs of the tenebrionid beetles because the fused elytra means that they cannot kill them by biting into their back (because the elytra cavity underneath means that the covering has a gap underneath. If they eat from the head, they can kill it right away. Even the lizards try to get them by the head if they can.

By: Vernon, Date: 11 October 2010

Hi Vernon, I'm sorry I didn't get to meet you at the lodge! Thanks for your information on the behaviour of scorpions feeding on the tenebrionid beetles. Interesting about the mist belt, during my month there I experienced four days of heavy mist brought in by the cold west wind. We must be just on the edge of the mist belt. According to some of the info I read before going up to Sossusvlei, the Numib Mountains stop any further inland movement. Not sure if it's common, but I certainly had some amazing mornings in the mist! As far as identifying which of the 200 or so tenebrionid beetles this particular one was, I have no idea. I did think that it was strange for a mist-catching beetle to suffer this fate, so perhaps the scorpion theory explains it. Thanks again, Phill

By: Phill Steffny, Date: 11 October 2010

Phill,

I'm glad to see you read your comments. At Sossusvlei Desert Lodge, you are around 100 kilometers from the ocean (on the boundary with the Namib Naukluft Park - that is far from the fog zone. Fog can extend as far as the Namib Escarpment (east of the Nubib Mountains), but that is rare. Fog reaches Sossusvlei Desert Lodge around 8 times in the year, usually between July and October, but it can be any time. But these few fog events leave so little moisture as to have virtually no effect. Even at Sossusvlei, in the interior Namib, where you are some 50-ish kilometers from the ocean, the fog isn't very significant in terms of what grows there, and there isn't any fog basking done by beetles (to our knowledge anyway).

The presence of some fog-zone plants at Sossusvlei is purely a result of the exceptional rain there was in 2001, 2006 and 2008 down at Sossusvlei. Fog reaches Sossusvlei about 50 days of the year - sometimes even in the midle of December - you get down there and freeze and get back to the lodge and it is 38 Celsius. Within the fog zone the fog is coming in well over 100 days in the year - more like 200 in most of it. If you drive to Swakopmund from the lodge, that area is very easy to see as you start seeing the fog-zone plants - more succulent type stuff and not as much grass. To actually see the fog-basking beetles, even near the coast, you really go to the dunes right near the coast where the fog is the most heavy - the fog needs to be so thick that the animal actually gets wet.

I hope you enjoyed your time as Sossusvlei - it really is as you say - you find new stuff all the time.

By: Vernon, Date: 12 October 2010