14th December 2019
First look at marsupial hair – antechinus agilis
The first striking feature is the similarity with the hair of rodents and shrews despite a common ancester now thought to be 170 mya. The guard hair is a classic dielectric antenna that actually looks more sophisticated than mice and shrews. It has a highly symmetrical cuticle pattern in the tapering section that enables some accurate mapping. This mapping will be crucial to identify the function of the cuticle pattern. The patterns fit a (1+COS)^2 theme and could be, what is called, a meta-surface for guiding surface waves and prevent them being radiated in a taper. By looking back at mouse and shrew hair the same patterns can be seen in the tapering section but the patterns swirl and rotate so it is difficult to map. Antechinus will enable the patterns to be accurate mapped so that photonics experts can explain the mechanisms at work.
16th February 2019
First video evidence for infrared sensors in small mammals
After a concentrated effort at Peter Whieldons wildlife photography centre we have at last got very good animal behaviour evidence for infrared sensors in rats and mice. The plan was to manufacture an owl replica matching the infrared emission of a tawny owls eyes. We call it “Hot Eyes” and it can be remotely heated. We used the Merlin camera over the Xmas holiday to film rats near a bird feeder and got confirmation that rats only take notice when it is warm. The adults rapidly learn it is not a real threat but young rats stay extremely nervous. The key experiment though used a Bushnell Trophy trail cam. It is not widely known that these cameras produce a lot of infrared when the near-infrared LED switches on at night. We can block the infrared with a glass sheet so we can run a controlled experiment to test for infrared sensitivity. The results were stark – no unusual behaviour with the glass, frozen to the spot without. All the results are summarized in this video and it is also a good source for an overview of our evidence so far.
6th December 2018
Visit to Melbourne Museum to visit Dr Kevin Rowe, Senior Curator of Mammals at Museums Victoria
Kevin made available a range of species including rats, antechinus, platypus and echidna and a fairly low powered microscope. There were no signs of any infrared adaptations in the latter two. Rats had the classic hair anatomy. So the focus was on antechinus a marsupial mouse. With the limitations of the microscope the hair anatomy looked classic with guard hairs and banded underfur. It was a surprise to see such a distantly related animal have hair anatomy so close to common rodents. Kevin believes they last diverged 160-180 mya.
Melbourne Museum has been approached to try to get hair samples from antechinus but both import and export paperwork is required.
4th April 2018
The sensor structures in the European rabbit and the house mouse are strikingly similar despite being distantly related (87 mya). The shrew family is even more distantly related to both (97 mya) and has a different sensor design. It would be very interesting to see if small marsupials have sensors to place the common ancestor beyond 150 mya.
29th March 2018
The team of top scientists checking the website has been extended. Professor Harvey Rutt of Southampton University has agreed to review the evidence and use his extensive experience of infrared sources and materials to contribute to the intriguing conclusion that the hair anatomy is tuned to 16 microns. Dr Neil Gordon of Aston University has a wealth of experience in infrared engineering following a long career at RSRE/DERA Malvern on infrared sensors and emitters. Philip Oakley of Leonardo Edinburgh has broad experience in infrared and optical engineering.
10th March 2018
The B. J. Teerink book on “The Hair of W. European mammals” deals exclusively with guard hair because underfur is not sufficiently different to associate with the species. Teerink adopts the term ‘shield’ for the broad part of the distal end of the hair that the author interprets as an infrared antenna. The book has photographs of hair and a scale that enables the details of the shield to be measured. It is summarized below :
Most small rodents and hares have tuning around 10 microns which is the optimum wavelength for thermal imaging corresponding to the peak of infrared energy and a transparent window in the atmosphere. Notably exceptions are the European mole and dormice. The mole has no need for 360 degree threat warning but it may have sensors in the head or rear. Dormice also have very few predators with a mainly arboreal active life and seem to have rejected infrared threat warning.
Shrews are distantly related to rodents and have a different antenna concept with band spacing of 8.4 microns although we do not know enough yet to predict a wavelength. The photo below of the common shrew is compressed 16x. The tip is on the left.
24th February 2018
The zigzag hair in the house mouse Mus musculus and common shrew Sorex araneus have very similar tuning but have a different antenna concept. These animals are distantly related and the strong similarity in tuning (see left hand side of diagram below) suggests convergent evolution on a wavelength around 16 microns. The distal radiating awns are different: reflection grating and end-fire antenna respectively but both appear to project the emitted radiation sideways (perhaps to reduce their visibility to snakes).
A tuned value of 16 microns is difficult to explain in view of the absence of any known source and absorption in the hair itself. The next step is to get this interpretation confirmed. If we are forced to conclude the wavelength is far-infrared 16 microns then we can move onto the next problem,
26th February 2018
Website goes alive at last and URL sent to a selection of people for first reaction.