Tick question

[Wild-Woman]

After being bitten in the summer by a tick, I've obviously been interested in knowing a bit more about them. I'm ok...no nasty side effects (well not ones that you'd notice anyway) but for my own curiosity, I'd like to know why the young nymph has six legs and the adult eight?

[earthdragon64]

I don't know about the legs, but the following link is for a website with a lot of information about ticks, the diseases they carry, symptoms etc.

Ticks - Lyme Disease & other tick borne diseases in Britain

What seems to be the main problem with tick bites is that GPs don't know enough about them and their effects so diagnosis of anything nasty can be delayed. I'm lucky living where I do as the local GPs are very clued up.

There is usually also a quick health and safety talk about ticks and their bites at the start of most field trips run by a wide range of wildlife related societies in this area. Even though most of the locals have heard it before, it's still important as visitors from other areas often attend field trips and quite a few haven't heard the information before.

[The Woodman]

It's a question I've often wondered about W-W and have just dug British Wildlife April 2009 and eaten my Camembert and toast reading the article "British ticks".

I'm none the wiser regarding the leg issue but it's only the larvae that have three pairs of legs. The life cycle of Ixodid ticks is egg, larva, nymph and adult.

It's a fascinating article all the same and I too would be interested in why.

[Rossco]

I suppose it's the same as asking why does a typical maggot have no legs, whereas the adult fly has three pairs? Perhaps not a direct comparison, but I think the morphological variation between life stages is a consequence of it being honed by natural selection to fit a particular niche.

Depending on if the tick is a one host, two host, three host or more than three host species, each stage in the life-cycle may seek a different host species. Perhaps the multiple host strategy is the ancestral condition where three pairs of legs conferred a selective advantage on the larvae when seeking out and sticking to a particular group of host animals.

Alternatively, the reduced leg count in the larvae may represent the morphological consequence of investing less energy in constructing a body. Three pairs of legs may be more than adequate in the larvae, but in the adult a fourth pair may be crucial for reproduction, etc.

These are just theories. I'm writing some stuff on ticks at the moment and from all the sources I've used I've found no reference to what the significance of the reduced leg count in tick larvae may be. The same also goes for the mites, as many species go through even more developmental stages, including six-legged larva and peculiar stages that do nothing more than simply 'rest' and give rise to the next stage - akin to pupation in insects.

These small arachnids are a much maligned, but fascinating and enigmatic group of animals.

[The Woodman]

I was thinking along the lines of your theories Rossco but am in no position to advance them.

[rangersarah2]

Originally Posted by earthdragon64

I don't know about the legs, but the following link is for a website with a lot of information about ticks, the diseases they carry, symptoms etc.

Ticks - Lyme Disease & other tick borne diseases in Britain

What seems to be the main problem with tick bites is that GPs don't know enough about them and their effects so diagnosis of anything nasty can be delayed. I'm lucky living where I do as the local GPs are very clued up.

There is usually also a quick health and safety talk about ticks and their bites at the start of most field trips run by a wide range of wildlife related societies in this area. Even though most of the locals have heard it before, it's still important as visitors from other areas often attend field trips and quite a few haven't heard the information before.

Good comment about doctors. I went to see mine when I started feeling dreadful - at the time I was working in a deer park. I asked the doctor about Lyme Disease but was told that there was no such thing and that I was depressed! Good huh?

[charlieb]

Next time you find a tick send it to the recording scheme: HPA - Tick Recording Scheme

[JRsbugs]

Originally Posted by charlieb

Next time you find a tick send it to the recording scheme: HPA - Tick Recording Scheme

I couldn't resist... I'll be with you in a tick!

[Wild-Woman]

Originally Posted by Rossco

I suppose it's the same as asking why does a typical maggot have no legs, whereas the adult fly has three pairs? Perhaps not a direct comparison, but I think the morphological variation between life stages is a consequence of it being honed by natural selection to fit a particular niche.

Depending on if the tick is a one host, two host, three host or more than three host species, each stage in the life-cycle may seek a different host species. Perhaps the multiple host strategy is the ancestral condition where three pairs of legs conferred a selective advantage on the larvae when seeking out and sticking to a particular group of host animals.

Alternatively, the reduced leg count in the larvae may represent the morphological consequence of investing less energy in constructing a body. Three pairs of legs may be more than adequate in the larvae, but in the adult a fourth pair may be crucial for reproduction, etc.

These are just theories. I'm writing some stuff on ticks at the moment and from all the sources I've used I've found no reference to what the significance of the reduced leg count in tick larvae may be. The same also goes for the mites, as many species go through even more developmental stages, including six-legged larva and peculiar stages that do nothing more than simply 'rest' and give rise to the next stage - akin to pupation in insects.

These small arachnids are a much maligned, but fascinating and enigmatic group of animals.

Sounds a very feasible theory. Would make some sense. Perhaps as you say the 4th pair have a function that we do not understand yet.