Unfortunately, as much of the monotreme fossil record is in the form of tooth and jaw fragments (reviewed in ), the basal form of the monotreme venom system is unknown. In extant monotremes, venom delivery systems are located in the hind limbs. (reviewed in )), and the Monotremata (platypus Ornithorhynchus anatinus). These include the Insectivora (the short-tailed shrew Blarina brevicauda, the European water shrew Neomys fodiens, the Mediterranean water shrew Neomys anomalus, and the Hispaniolan solenodon Solenodon paradoxus, with some indication that other members of this order may also be venomous (reviewed in )), the Chiroptera (the common vampire bat Desmodus rotundus, the hairy-legged vampire bat Diphylla ecaudata, and the white-winged vampire bat Diaemus youngi ), the Primates (slow lorises Nycticebus sp. Based on the recent expanded definition of venom as a physiologically or biochemically disruptive substance that is secreted from a specialized gland and delivered via a specialized delivery system, there are four lineages of venomous mammals. In contrast, the venomous mammalian lineages have been largely unstudied until recently. The reptiles are perhaps the best known group of venomous vertebrates, and the venom of many species is well characterized. ![]() Venom has evolved independently across multiple vertebrate and invertebrate lineages. An improved characterization of mammalian venoms will not only yield new toxins with potential therapeutic uses, but will also aid in our understanding of the way that this unusual trait evolves. We also outline several research directions and outstanding questions that would be productive to address in future research. Further, we synthesize current ideas about the evolution of the venom system, which in the platypus is likely to have been retained from a venomous ancestor, whilst being lost in the echidnas. Here we review the physiology of platypus and echidna crural (venom) systems as well as pharmacological and genomic studies of monotreme toxins. However, the availability of the platypus genome and increasingly sophisticated genomic tools has allowed us to characterize platypus toxins, and provides a means of reconstructing the evolutionary history of monotreme venom. Until recently, monotreme venom was poorly understood. So far, we haven’t been able to stump a class yet, with the keen, observant eyes of children quickly deducing the identity of our platypus skeleton.The monotremes (platypuses and echidnas) represent one of only four extant venomous mammalian lineages. “assembled”) skeleton of various animals and put their detective hats on to work out the identity of the animal, with the answer revealed by the taxidermed (i.e. ![]() This particular specimen is a star of our Natural History Museum activity Form and Function, where students deduce aspects of the ecology, habitat and diet of animals based on their skeletons. To sift prey from mud and gravel, the platypus uses the electroreceptors in its leathery bill to detect the electrical signals produced by the muscle contractions of small prey. When a platypus is not busy hunting for small invertebrates on the bottom of a river bed, it spends the most of its time in a short, simple burrow in the side of the river bank. The platypus, known scientifically as Ornithorhynchus anatinus, lives in relatively undisturbed freshwater streams or rivers. Australia is home to two monotremes (egg-laying mammals) – the short-beaked echidna and the platypus. In keeping with the Monotreme theme of last month’s specimen, this month we will take a closer look at the platypus. ![]() What Body Part is That: Label the Brain.
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