Carnivorous snail

While 'carnivorous' and 'snail' are two words that most people wouldn't expect to find next to one another, these slow moving predators are actually quite common in some regions of the wet-tropics.  

 

This is one of our local carnivorous snails, Strangesta sp. (Rhytididae). Here is a series of photos showing it attacking and consuming a young Hadra webbi. Strangesta spp. have an extendible mouth part known as the buccal mass. It is a long, cylindrical muscular organ - the white tissue visible in the last image. This is extended inside the shell of the prey to enable the radular to access the soft tissue.

 

Colour variation in captive Onchestus rentzi

For a while now we have been captive breeding a genetic population of 'lichen-form' Crowned Stick Insects (Onchestus rentzi). Although these insects are somewhat variable in colour, the most common colour form is brown. Over recent years we have noticed some individuals within our main breeding colony exhibiting a lichen-like trait. Last year we decided to experiment with a few of those to see if the trait was genetic or the result of environmental influences including lighting and food plant.

We separated three young lichen-form females and let them mature in isolation, but kept them under the same conditions as our main group. The three females matured and began to lay eggs without being mated. The species is believed to be parthenogenetic but we had never tested it, so we were quite interested to see if the eggs they laid were even fertile. Those eggs are now hatching and the resultant offspring are indeed the same colouration as the females that produced them.

Two or the original three females are still alive and laying eggs on a daily basis. Recently though, the eggs that they are producing are different in appearance than previously. Normally the eggs are uniform brown, ranging from tan through to a chocolate colour - exactly what these individuals have been producing until now. These recent eggs are two-tone like the insects themselves, with a splash of white across the posterior end. We are not sure why this is occurring but will continue to observe and document these insects with interest.

One of the original 'lichen-form' females.

The eggs laid recently exhibiting an unusual colour trait.

Paralysed and waiting



We accidentally broke open a mud-dauber wasp nest under our house while moving some equipment. The mud cells were packed with paralysed jumping spiders of multiple species. The culprit was a slender orange wasp belonging to the genus Sceliphron obviously specialising in spiders from the family Salticidae. 

The adult female wasp captures and paralyses the spiders and then packs them into the mud cells. She then lays an egg before closing the cell over with mud. The spiders are paralysed, but not killed so that they do not rot and the wasp larva can consume them over time. I rearranged the contents of one cell for this photograph. A wasp larva is in the centre in the process of consuming a spider.

Break the drought!

It has been quite a while between posts, time flies!  We've been busy running our Minibeast Wildlife operation and working on a book...or two! We are currently working on the first of a series on the husbandry of Australian phasmids.

To get things rolling again here are some images taken over the past few months around around our region.

Jungle huntsman, Heteropoda jugulans

Cotton Harlequin Bug, Tectocoris diophthalmus. This species can be found feeding on a variety of Hibiscus spp.

A very cryptic crab spider, Stephanopis sp.

A hatchling Kirby's Stick Insect, Xeroderus kirbii. This specimen was found on Melaleuca just west of Kuranda.

Argyrodes sp. These bizarre spiders are kleptoparasites found in and around the webs of the large orb-weavers Nephila pilipes.

An assassin bug Gminatus sp. feeding upon a caterpillar.

Big eyes at Cape Tribulation

A couple of snaps from Cape Tribulation this week, featuring a couple of invertebrates with very impressive eyes.

A small Monkey Grasshopper (Biroella sp.). The large red compound eyes combined with the black pseudopupils give these grasshoppers a charasmatic appearance.

A Net-casting Spider (Deinopis subrufa) in the latter stages of producing an egg sac. The spider was continually turning the egg sac with her legs whilst adding silk in a dabbing motion with her spinnerets. Nest-casting Spiders are visual hunters. Two of their eyes are huge allowing them to accurately strike their prey with their net.

Another impressive catch

We found this amazing scene in the foliage beside our driveway. A small Ornate crab spider (Poecilothomisus speciosus) had captured an adult male Jungle huntsman (Heteropoda jugulans). Crab spiders are renowned for capturing prey larger than themselves, but taking down a predator of this size is very impressive. Even more remarkable was that the crab spider was operating on 5 legs - it had lost three some time prior on its right side.

Punching above their weight

Crab spiders (Thomisidae) are ambush hunters, spending most of their time waiting motionless for invertebrate prey to come within reach. When they do strike, they simply grasp their prey with their front two pairs of legs and pull it toward their fangs. Their venom appears to be very fast acting as they have the ability to subdue animals many times their own weight and do so quickly with a minimum of fuss. While filming crab spiders in Costa Rica in 2011 we shot multiple sequences with of them capturing beetles. Each time the beetle were captured they would shudder and die within seconds. Given that these spiders are often much smaller than their prey, and do not use silk to assist them, having a venom which if fast acting is a necessity.

This tiny crab spider (possibly a juvenile Thomisus spectabilis) was photographed last night in our yard. It has captured a much larger katydid (Caedicia sp.)

 

 

A cryptic crab spider (Stephanopis sp.) at Cape Tribulation with large prey – this time a Phricta spinosa nymph.