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Facts Of Life - Father & Son Talk
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| [Note Guidelines] Photographer's Note |
Porcellio scaber
(Woodlouse/Slater)
Kingdom Animalia
Phylum Arthropoda
Subphylum Crustacea
Class Malacostraca
Order Isopoda
Suborder Oniscoidea
Family Porcellionidae
Genus Porcellio
Species scaber
There are four common species of woodlice found in metropolitan regions of New Zealand. They are Porcellio scaber, Armadillidium vulgare, Porcellio pruinosus and Eluma purpurascens. It is relatively easy to distinguish between these species. There are also numerous native species found in native forest areas.
Porcellio scaber is generally a greyish colour and has a head with three "lobes". P.pruinosis does not have an obviously lobed head and the posterior portions of the dorsal plates are not hook shaped as in p.scaber. When disturbed, both Eluma purpurascens and Armadillidium vulgare roll into a ball shape for protection. In the USA Armadillidium species are sometimes referred to as pill-bugs, non-rolling species may be referred to as sow-bugs.
E.purpurascens can be distinguished form A.vulgare by observing the eyes. E.purpurascens has a single eye, and tends to be pinkish in colour, whereas A.vulgare has a compound eye.
Behaviour
Many of the behavioural responses of woodlice are concerned with water conservation and the need to avoid desiccation. Most woodlice are terrestrial (most other crustacea are aquatic), however they lack some of the structures found in other terrestrial arthropods such as insects and spiders.
Woodlice have a relatively high surface area to volume ratio and are therefore likely to loose water by diffusion more quickly than many other species. They also lack a waxy, waterproof cuticle and so water will readily diffuse through their exoskeleton more rapidly than in other arthropods.
Their respiratory surfaces are simple pseudo-lungs with a pore opening to the outside to allow exchange of gases in and out of the lung. This pore is unable to be closed and so water is able to continuously diffuse (or transpire) from the inner surface of the psuedo-lung out into the surroundings.
To replace water lost by transpirational losses, woodlice are able to take up water through their uropods. These structures are pressed against moist surfaces, capillary action results in water absorption.
The behaviour of the woodlice helps it to prevent excessive water loss and so it is able to successfully live in a range of terrestrial habitats.
1. Humidity
Porcellio scaber show a kinesis type responses to humidity. They show both an increased speed of movement (=orhtokinesis) and increased rate of turning (=klinokinesis) in dry conditions and slower rates of movement in more humid conditions. This response will result in them accumulating in more humid regions.
These responses mean that the animals will spend more time in humid conditions and so will not loose water from their bodies.
It has been reported (Sutton, Woodlice, 1972) that woodlice taken from very damp conditions show a different reaction. They may either show no difference in their reaction to changes in humidty or may even actively avoid the humid regions in preference for the drier regions. We have observed differences in behaviour of woodlice after varying lengths of time in dry conditions which would support this.
2. Temperature
Woodlice show a positive orthokinesis (speed of movement) as the temperature increases or decrease from their preferred value. Their rate of turning also seems to show a similar response.
By moving more rapidly they are likely to spend less time in these unfavourable conditions and therefore will avoid unnecessary desiccation.
3. Light
Woodlice show a negative phototaxis.This would will result in them moving away from bright conditions towards darker regions. Brighter conditions tend to be drier and warmer than dark conditions so this behaviour will again result in decreased desiccation.
4. Other objects
Woodlice show a positive thigmokinesis. This means they are less active when more of their body surface is in contact with other objects (including other woodlice). They will move around so that the maximum amount of their body is in contact with other objects.
This behaviour results in woodlice forming groups or clumps and also means they will tend to congregate in cracks and crevices. In all these cases they will have better protection from desiccation and also predators
(Information from 'Woodlice On Line')
This looks like a 'Father & Son' talk to me .... you know,coping with puberty and that.
"If your exoskeleton starts to peel off son,don't worry about it.It's all part of growing up"
Hope you enjoy this shot.
Cheers
Steve |
red45, haraprasan, rcrick, Janice, cicindela, techranger has marked this note useful
Only registered TrekNature members may rate photo notes. |
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- clnaef
![Gold Star Critiquer/Gold Star Workshop Editor/Gold Note Writer [C: 770 W: 59 N: 640]](http://i1.treknature.com/misc/g-g-g.gif)
(6620) - [2008-09-02 2:15]
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Bonjour,
Un bel ensemble bien documenté.
Bonne journée.
clnaef
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- red45
(26909)
- [2008-09-02 2:20]
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Haha, Steve, great idea! I must mention, that my father NEVER talk with me about exoskeleton. Now I feel I missed something important...
I like woodlice [I don't know why exactly] and this father/son scene looks great!
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- rcrick
![Gold Star Critiquer/Silver Workshop Editor/Gold Note Writer [C: 647 W: 42 N: 1198]](http://i1.treknature.com/misc/g-s-g.gif)
(3854) - [2008-09-02 2:43]
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Hi Steve,
What a composition just excellent mate, love the detail and the colours, impressive notes, nice capture, t.f.s
Cheers Rick :)
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- Janice
(17708)
- [2008-09-02 3:33]
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Interesting notes Steve - I've had no thoughts before on the life of slaters!! And it's a good shot of 'father and son' here. They looks good together
TFS
Janice
Excellent scene and note. Funny title.
Lovely background which fits their natural environnement.
The exosqueleton is burnt. An exposure bias between -1 and -2 might have been appropriate. But this is just a small nit in a great shot.
TFS
JM
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- joey
(21340)
- [2008-09-02 5:55]
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Hehe Great title :-))
Another very impressive macro.
The amount of detail is excellent.
Very sharp.
Great composition.
Well done,
Joe
Hi Steve!
Very good and funny title to this unique photo. There are only few (if I remember...) picture of Isopoda in TN gallery, so this one is a very important contibution :)
Very nice details, sharpness and colours, but my favourite part of this presentation is very informative note :)
I would say - now it's time for other 3 common Isopoda species ;>
Best greetings from Lodz,
Radomir
An important part of growing up.. those father/son talks... ;)
I love it... :0
Larry
Namastay Steve,
A nice capture of this father and son wood lice. Very well composed with sharp details. You have mastered the 150 so soon. Thanks a lot for sharing.
Sincerely
Hara
![Gold Star Critiquer/Gold Note Writer [C: 129 W: 2 N: 400]](http://i1.treknature.com/misc/g-n-g.gif)
(1293)