Tuesday, 13 July 2010

Why'd it have to be snakes leeches?

The rainforest is a fairly benign place. Apart from the stinging trees, of course. And 6m-long scrub pythons that can give a nasty bite. And cassowaries with claws that can razor open an adversary. Not to mention venomous small-eyed snakes that lie just where you're about to put your sandalled foot. But apart from that, there's not much around here that will do lasting damage.

There are, however, bucketloads of animals and plants that will cause inconvenience. I know this, because I've encountered them all. Numerous times.

The leeches are lively at the moment. They lurk in leaf litter and on low vegetation, waiting for a meal to pass by. Most often, that meal is a pademelon, but sometimes that meal is me.

A leech from the garden.

These leeches (family Haemadipsidae) have two cutting jaws, which leave a characteristic wound pattern. (On my heel.) Other families of blood-feeding leeches, such as the medicinal leech, have three jaws that make a Y-shaped incision. A large number of species are jawless and either insert a needle-sharp proboscis into their victim or swallow their prey whole. Fortunately, in the latter case, their prey is usually small, soft-bodied and spineless.

They might turn up anywhere. This one was resting on the garden hose, looking as though it might be digesting a gutful of macropod blood. (Anterior to the right.)

Lateral view of the leech. The posterior sucker (right) is used to anchor the animal.

Business end of the leech. The anterior sucker is just visible as a small, pale halo.


JK said...

Hi Snail,

A leech bite is always a must for explorers of the rainforest realm! :D



How tolerant are they of desiccation & how tolerant are they of immersion? Do they ever enter water voluntarily?

Susan said...

oh dear, I fear I shall never joyfully go walking with you into the damp quagmire!! I try to keep calm when there are bloodsuckers attached to me, but really?? I'm shaking inside, and can't wait to shake the salt!

Tyto Tony said...

It's the itching after the suckers quit and healing starts that bugs me. Got first leech in six years in Tyto the other day. Surprising, since I'm often in waist-high grasses chasing after birds. It appeared to be climbing toward bleeding scratch on my leg. Do they sense blood, or react merely to warmth and movement?

Snail said...

JK, a leech bite and a trail of blood is a badge of honour!

Snail said...

Aydin, they desiccate very easily. I kept one in a jar overnight and it had dried out by morning.

Not sure about immersion. They live in leaf litter and very damp moss, so they must have some tolerance. I don't think they would go into water, but am not sure.

Snail said...

Susan, proper footwear and spray-on insect repellent will deter them. Not the ones that drop from trees, of course. I know of two people who have ended up with a small leech feeding on the inside of an eyelid.

Just thought I'd mention that.

Snail said...

Tony, I have a load of antihistamines here to deal with leech and tick bites. I am sporting two of each at the moment! They're driving me crazy.

I know terrestrial leeches deploy a range of senses to locate a meal. They can detect light, temperature and vibration. I think they can also pick up chemical signals, but I don't know whether that includes blood. It would make sense if they could home in on bleeding prey.

Snail said...

Aydin, just found this:

>> Land leeches are common on the ground or in low foliage in wet rain forests. In drier forests they may be found on the ground in seepage moistened places. Most do not enter water and cannot swim, but can survive periods of immersion. <<

Lulu Stader said...


Sherrie Y said...

(sigh) Just proves to me that no matter where you go, there is always some self-serving sucker ready to make life uncomfortable.

Snail said...

Lulu, I understand!

We used to show undergrads the most fascinating footage of a medicinal leech (three jaws) cutting through a piece of an animal skin that was warmed with body temp saline. The camera was on one side of the skin, the leech on the other. Amazing stuff.

Snail said...

Sherrie, ain't that the truth!

Anonymous said...

B - once upon a time I drove a car through a shallow NQ rainforest stream crossing and stopped just on the other side to take a photo - lo and behold a dozen or so leeches came trooping out the stream-side leaf litter, ignoring my juicy bare feet, and marched up to the spot just below the car's exhaust muffler and tried climbing up the grass stalks underneath to get to it. I was insulted! (BTW re: photo of your heel - 1 observation - you need more sun!) W

Snail said...

That could be a handy tip, W. I should park on the grass ... er ... moss in the garden and see what I get.

As for the alabaster-like paleness (if not smoothness) of my heel --- I iz in a rainforest. On the Atherton Tablelands. I have heard of the sun but it's a while since I've seen it.

macromite said...

Ugh, what memories you invoke. The only thing I really loathe in the rainforest are the leeches. Stinging trees are unfortunate, paralysis tick at least phylogenetically interesting (and mostly in the drier scrub), and I haven't been snake bit except when it was my own fault. But leeches - they act so luridly lustful for your blood and are so slimy - just the thought of that stretching and waving and inching, shudder! I know of nothing else that could make a beautiful, moss covered log a place for me to avoid.

Small ones in the eye must be relatively common. I was once sent a series of sections on slides of an 'insect' from someone's eye - and didn't recognise the leech until I got to the slide with the sucker.

Only leeches here in Alberta are aquatic. Some are alleged to bite, but mostly ducks. The majority that I see are predators of snails - so they may be more loathsome to you - but they help keep the loons fed on our fishless lake.

Snail said...

Macromite, I get leeches and ticks here. I blame the mammal fauna!

There is something definitely disturbing about those little slimy critters searching for blood. I think I have contributed enough to leechdom over the years. They can back off now.

Russell Constable said...

North Queensland leeches appear to be heat seekers.
I used to do a demonstration of this when I was a smoker. I would light up my zippo lighter and allow it to warm up,then close it and leave it on the forest floor. Within about 5 minutes at least 1 leech would be on the lighter.

Denis Wilson said...

Hi Snail
Your leeches are somewhat different to mine
I remember reading about the two jaws and three jaws, but I have not ever see the marks quite so clearly. Mine have the 3 jaws anyway.
PS Loved the Patsycline and Darlocline story.
Apostle Birds can be seen near Dubbo, and West Wyalong (depending on which road you take). Definite preference for Callitris forest and open Eucalypt country. But further south, no Callitris, so few Apostle Birds.

Snail said...

Russ, sounds like the only way to avoid leeches is to adopt the solution Arnie arrived at when facing the Predator: covering up with cold mud.

Snail said...

Denis, that's a very speccy leech with its racing stripe!

I'm usually heading north out of Coonabarabran by the time I remember to look for apostlebirds. As you say, plenty of them hanging around in the Pilliga Scrub.

Russell Constable said...

Hey snail re the cold mud ...you would still be breathing in which case co2 would attract mosquitoes. You would still be moving leaving you vulnerable to ticks and scrub itch mites.Movement could bring you into contact with stinging tree too. I have deduced that being stone cold dead would offer immunity to all of these perils though it may not be a practical option. Leeches suck!