SummarySeveral lizard species that live in arid areas have developed special abilities to collect water with their bodies' surfaces and to ingest the so collected moisture. This is called rain- or moisture-harvesting. The water can originate from air humidity, fog, dew, rain or even from humid soil. The integument (i.e., the skin plus skin derivatives such as scales) has developed features so that the water spreads and is soaked into a capillary system in between the reptiles' scales. Within this capillary system the water is transported to the mouth where it is ingested. We have investigated three different lizard species which have developed the ability for moisture harvesting independently, viz. the Australian thorny devil (Moloch horridus), the Arabian toadhead agama (Phrynocephalus arabicus) and the Texas horned lizard (Phrynosoma cornutum). All three lizards have a honeycomb like micro ornamentation on the outer surface of the scales and a complex capillary system in between the scales. By investigation of individual scales and by producing and characterising polymer replicas of the reptiles' integuments, we found that the honeycomb like structures render the surface superhydrophilic, most likely by holding a water film physically stable. Furthermore, the condensation of air humidity is improved on this surface by about 100% in comparison to unstructured surfaces. This allows the animals to collect moisture with their entire body surface. The collected water is transported into the capillary system. For Phrynosoma cornutum we found the interesting effect that, in contrast to the other two investigated species, the water flow in the capillary system is not uniform but directed to the mouth. Taken together we found that the micro ornamentation yields a superhydrophilic surface, and the semi-tubular capillaries allow for an efficient passive – and for Phrynosoma directed – transport of water.

The sandfish (Scincidae: Scincus scincus) is a lizard having outstanding skin properties. The scales show low friction behaviour and high abrasion resistance. After giving molecular support by DNA and protein analysis in Part 1 for increased glycosylation of the skins β-keratins, in this study the effect of glycans for friction reduction was investigated by (1) ammonium-based keratinolysis of skin exuviae and applying a β-keratin film on a glass surface and by (2) β-elimination based deglycosylation of β-keratins and immobilization of liberated glycans on a glass surface via silanisation. Both techniques resemble the natural model in the species investigated, the sandfish Scincus scincus and the Berber skink Eumeces schneideri. In the sandfish, a decreased friction coefficient was found by friction angle measurements, and a low adhesion force was measured by investigation with atomic force microscopy (AFM). These characteristics are possibly based by prevention of the formation of van der Waals bonds. This low adhesion force correlates with low friction and has a positive impact on abrasion resistance. A monosaccharide analysis confirmed the presence of carbohydrates.

The Sandfish (Scincidae: Scincus Scincus) Is a Lizard Capable of Moving through Desert Sand in a Swimming-Like Fashion. the Epidermis of this Lizard Shows a High Resistance against Abrasion Together with a Low Friction to Sand as an Adaption to a Subterranean Life below the Desert’s Surface, Outperforming even Steel. the Low Friction Is Mainly Caused by Chemical Composition of the Scales, which Consist of Glycosylated β-Keratins. in this Study, the Friction, the Micro-Structure, the Glycosylation of the β-Keratin Proteins and β-Keratin Coding DNA of the Sandfish in Comparison to other Reptilian Species Was Investigated, Mainly with the Closely Related Berber Skink (Scincidae: Eumeces Schneideri) and another Sand Swimming Species, the Not Closer Related Shovel-Snouted Lizard (Lacertidae: Meroles Anchietae). Glycosylated β-Keratins of the Sandfish, Visualized with Different Lectins Resulted in O-Linked Glycans through PNA Employed as Carbohydrate Marker. Furthermore, the Glycosylation of β-Keratins in Various Squamatean Species Was Investigated and All Species Tested Were Found Positive; however, it Seems Like both Sand Swimming Species Examined Have a much Stronger Glycosylation of their β-Keratins. in Order to Prove this Finding through a Genetic Foundation, DNA of a β-Keratin Coding Gene of the Sandfish Was Sequenced and Compared with a Homologue Gene of Eumeces Schneideri. by Comparison of the Protein Sequence, a Higher Abundance of O-Glycosylation Sites Was Found in the Sandfish (enabled through the Amino Acids Serine and Threonine), Giving Molecular Support for a Higher Glycosylation of the β-Keratins in this Species.

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The present study investigates foraging and territorial behaviour of the strawberry poison frog (Oophaga pumilio) in dependence of the presence of formicine and myrmicine ants, which constitute the main food source of the frogs. Species of the formicine ant genera Brachymyrmex and Paratrechina contain highly toxic alkaloids (pumiliotoxins), which the frogs incorporate and accumulate in their skin what may serve for predator deterrence. Twelve male frogs of two populations (primary and secondary forest) in Hitoy Cerere, Costa Rica, were observed each for a full day. Calling time, feeding attempts and time spent inside and outside the core area of their territories were recorded. Furthermore, twelve males of both populations were observed during the main foraging time to determine, whether the frogs search for prey in specific patches of their territories. The ants inside the core areas of twenty four frog territories were collected and classified to genus. Ants of the genera Brachymyrmex and Paratrechina were classified to species or morphospecies, respectively. The presence of formicine and myrmicine ants in territorial areas was compared to non-territorial sites. We found that formicine ants (Brachymyrmex and Paratrechina) were more present inside the territorial core areas than outside. The higher presence of these ants in the core areas was associated with longer foraging times. We verified that toxic alkaloids of the pumiliotoxin group are present in the dendrobatid frogs of Hitoy Cerere. The results of this study suggest that toxic diet may be linked to territoriality in this frog species.