The Eye of the Beholder
Beauty, as we all know, lies squarely in the eye of the beholder. Good news for those of us who wouldn’t grace the pages of ‘Hello’ or ‘Tatler’ when it comes to attracting a partner! But enough of such self-deprecation, we’re talking weird wildlife this week.
There are plenty of animals that invoke a strong response in people, but no group polarises people more than parasites. It’s a perfectly understandable human instinct to find them repulsive, and I use the word very carefully in this context. There are some schools of thought that suggest that the phenomenon of evolution stems from the principals of parasite-host interplay. As the parasite develops and gets better at something, so the host is forced to evolve to outfox it, which in turn pushes the parasite to step its game up once again, and so on. Combine this competitive progression with a few million years and you get from a starting point of molecular goo, to what you see today. The good news is that as long as we don’t really muck things up, this shouldn’t be the end point - it all depends upon how clever we are at parasitizing the planet!
Now, as this isn’t a vetinary column I am not going to go into (pardon the pun) internal parasites, but just linger on those creatures which make their living by living on other animals.
Firstly, what is a parasite? An animal which lives on another animal, but which takes nothing from it either directly or indirectly is a symbiant – rather like a barnacle on the fin of a humpback whale. When an animal living on, or in, another animal begins to have a damaging effect on the host or takes something directly from it like pre-digested food or blood, then it can be termed a parasite.
Ticks are an increasingly familiar part of the countryside and an almost daily part of life for dog owners who like to exercise their animals in woods or on the heaths. They are widely disliked, but even here there are fascinating life histories playing out. Ticks are arachnids, belonging to the same family as spiders, but they have vastly different life cycle. The larval tick only has six legs and, in most species, needs to feed before it can progress into a nymph and then on to an adult.
The only way to distinguish between a nymph and an adult tick is to check for genitals, and as these are microscopic I will not be encouraging anyone to venture that far into their world!
Unluckily for some, there are 13 species of tick found in Britain, with an associated 27 diseases transmitted by them, the best known of which is Lymes disease. Of the thirteen species, many are host specific; such as the sand martin tick, or the locally misnamed tortoise tick, which in our country fares rather better parasitizing lizards! In fact the dear little tortoise tick is the only species in this country to not be responsible for any domestic or human disease. Ahh.
Most ticks will be picked up by dogs or people without their knowing, when out and about and the tick will make it their business to find a nice warm spot away from the light to start to feed. This means that they will usually attach themselves to a bit of the body with a good blood supply and engorge themselves, swelling to 8 or 9 times their original size. They will then drop off and can remain in a state or well-fed torpor for many months.
If you find a tick on your dog or, horrors, yourself there is a very simple way to remove them. The trick to removing a tick is in getting the mouth parts out of the skin. Simply pulling the offending ectoparasite from your body will inevitably leave the mouth or capituli in place which can lead to secondary infection. Old fashioned methods to remove the whole tick range from burning the thing in an attempt to shock it into loosening its grip, to smearing it with butter to ‘suffocate’ it out. A better solution is available. Most outdoor pursuits shops, garden centres and vets will stock tick hooks, which are like tiny bent plastic forks. By following the instructions with these little gadgets, you will remove the tick with no fuss and without leaving any of the unwelcome personal guest behind! If you do remove a tick from yourself and in the intervening few days start coming down with flu-like symptoms, it’s worth getting checked out by a doctor and mentioning your recent visitor’s removal.
The reason why parasites have been on my mind, figuratively, this week follows a photograph sent to be from Peter Vernon with an identification plea attached. This thing had emerged from his hair after a visit to the woods and he was very keen – to say the least – to find out what he had given a lift to! I recognised it as a flat fly, however another email recipient, Phil Parr sent back this very interesting response, from a friend of his in Warwickshire.
This is a deer-fly, Liptoptena cervi, a true fly in the Family Hippoboscidae. They suck blood and the females give birth to live larvae which pupate immediately, thus the normal egg and larval stages are eliminated. The new adults emerge in autumn, fly onto trees and then drop onto passing animals. Once on a suitable animal, they shed their wings.
Now, that story reminds me of some of the most shockingly fantastic science fiction I have ever read or watched, the difference being that this is science fact! A beast that flies up onto tree branches in wait of passing victims, falls into place and then gets rid of its wings – presumably to make themselves even harder to dislodge. It may not be pretty, but it really is fascinating!