Animal of the Week July 16, 2012 -- nice weather for, er...

The constant misery of the UK summer this year is reportedly having disastrous effects for many species—from bats to bees, songbirds, puffins, and butterflies—breeding success is down and some are threatened with local extinction. The saying goes that it's nice weather for ducks, although I suspect even they aren't faring particularly well; I've not seen a great swell in duckling numbers, and while not actually ducks, I know of at least one coot nest on the men's bathing pond on Hampstead Heath that was destroyed in a storm. One animal, however, for which the weather does seem to be particularly good news is Arion vulgaris (Spanish slug).

 At it A vulgaris c Zollernalb

The Spanish slug is considered to be one of the most damaging invasive species in the UK, where it was first recorded in the 1950s. Originating in the Iberian peninsular, the slugs lay 400 eggs in a single brood, expecting some of these to be dessicated by the arid conditions there; unfortunately further north in Europe, the damp weather—oh the damp damp weather—means that entire clutches hatch successfully. Moreover, in the north of Europe, they might be interbreeding with their native cousins black slugs (Arion ater) and becoming frost resistant, so populations are not checked by winter cold.

Frost tolerant A ater c Prashanthns

Favouring cultivated or disturbed land, the Spanish slug is now one of the most familiar slugs to people in the UK. This year they have rather disgustingly reached almost plague proportions; wreaking havoc in allotments, gardens, and farms up and down the country. Many agriculturalists are facing devastated crops not only because of the wet weather but also because of enormous amounts of slug damage.

Slugs will eat almost anything, from growing plants, to carrion, to faeces. Sur le continent, the Spanish slugs have been attacking snail farms: once they've dined on l'escargot they sometimes lay their eggs in the empty shells. Slugs in general seem particularly attracted to other dead or dying slugs. Apparently—and this is where you may need to hold onto your lunches—slugs pose a road hazard, as more and more are drawn to casualties on roads they can create dangerously slippy slicks of squished slugs.

How can you combat slugs? Egg shells, sharp sand, and coffee grounds are all supposed to repel them from tender plants; obviously slug pellets are an option and sales have rocketed this year, but they make sure you use the ferric phosphate kind if you must. Beer traps may catch a few; but let's face it, you'll just end up face down in a drunken stupour, covered in slugs in your garden if you try this. Copper wire around plant pots will stop them climbing in, and of course there's the old salt trick -- although that's not much use for gardeners as salt ain't good for your plants.

Christine Walkden of the Gardeners' Question Time panel last week came up with this stomach churning suggestion related with far too much glee. Collect the slugs from your plants, put them on a patch of pavement, squash them underfoot, leave for a couple of hours for other slugs to hone in on the squashed slugs, go out and trample those underfoot, repeat. This is what I inadvertently ended up doing on my way to and from the pub walking alongside Dartmouth Park Reservoir on Monday evening.*

*AOTW does not advocate the killing of any animals, although I acknowledge that some level of pest control may be necessary. You can encourage other animals that feed on slugs into your garden, but actually, the habit of slugs to curl up into a tough ball and secrete noxious mucus means that many animals will only really eat slugs as a last resort: blackbirds and hedgehogs are likely to be your best friends; badgers and wild boar are also predators of slugs, but also not that great for your garden.

Slugs head to toe
1, Slugs have two pairs of tentacles: the smaller lower pair are used as chemosensors, essentially they're the slugs' sense of smell; the top pair are tipped by the slugs' eyes.

2, The sadle shaped mantle is the real business part of the slug, housing it's organs including it's digestive tract, genitals, and lungs.

3, On the right hand side of the mantle, slugs have a pneumostome, an opening through which air enters the mantle.

4, Slugs are hermaphrodites, although some species still only reproduce in pairs, some, such as Arion vulgaris, will self-fertilize and can produce a fertile brood, if no mates are available.

5, The large part of a slug is its foot, a large muscular organ that propels the slug around on a film of mucus secreted by the slug.

Animal of the Week July 9, 2012 -- Spot the difference #1

So, here is the first in a series (given my output perhaps of one) of ramblings about the differences between things. The idea was prompted by a text message from my sister Sarah on Sunday asking "What's the difference between shrimps & prawns". Fortunately I had recently investigated this myself, so was able to reply that it's actually more of a semantic thing than a phylogenetic thing; although on revisiting the subject, I find that actually that's not the whole story, and it really depends on who you speak to and where they are from.

Classic curvy prawn
(Penaeus monodon)

Classic shrimp back bend
(Pandalus borealis)

In certain fields, distinctions are made between shrimp and prawns. For example, taxonomists classify decapod crustaceans (a grouping that also includes crabs and lobsters) of the infraorder Caridea as shrimp and those of the suborder Dendrobranchiata as prawns. And to some extent this works for the scientists: shrimp have two pairs of pincers and a hooked body among other defining characters, and prawns have curved bodies and three pairs of pincers. However, many animals called shrimps (miracle shrimps, mantis shrimps, and some freshwater "shrimps") and some called prawns (the Dublin Bay prawn for example) belong to completely different groups of crustaceans—neither prawns nor shrimps.

In common day parlance, this division works in some circumstances. For once, the Aussies have it phylogenetically spot on. In Australia (sorry Sarah, I got this wrong), the phylogenetic distinction is quite rigorously enforced: prawns are those animals of the family Penaeidae (those most closely related to the tiger prawn), whereas shrimp are the Caridea.

Brown shrimp (Crangon crangon)

In England the size distinction between "prawns" and "shrimps" fits generally with the taxonomic division. The brown shrimp (Crangon crangon) caught around the UK, boiled, shelled, and "potted" deliciously in butter belongs to the Caridea and is indeed a shrimp, and big fat tiger prawns (Penaeus monodon) have a long curved body and three pairs of pincers, so are clearly prawns. However, the north Atlantic peeled prawn in the classic prawn cocktail (Pandalus borealis) is actually a shrimp. In North America the word prawn is rarely used, with even the largest members of the Dendrobranchiata being served as shrimp. To illustrate the problem further, the freshwater prawns of the genus Macrobrachium, popular in the cuisine of south and southeast Asia, are despite their large size, actually members of the Caridea. And in aquaculture, the term "shrimp farm" is becoming increasingly used for any attempts to cultivate any of these animals.
 

Prawn cocktail (phylogenetic shrimp)

So what is a prawn and what is a shrimp depends on your field of interest—phylogenetic, agricultural, or gustatory—and where you are from. The terms "prawn" and "shrimp" are both used as slang, again with regional preferences, to refer to someone who has a good body but an unattractive face, this use is derived from the practice of eating the body but throwing away the head of these crustaceans.

Animal of the Week July 2, 2012 -- New balls please

Wimbledon is in full swing once again which can mean only one thing: rain. But attendant to the rain delays are quirky stories to fill up allotted hours of airtime. With Cliff Richard conspicuous by his absence, our focus has been on Andy Murray's balls falling out of his shorts and on this week's animal of the week Parabuteo unicinctus (harris hawk), specifically Rufus, the hawk used to prevent pigeon delays should the rain ever cease.

Harris hawks, native to the more arid regions of the USA, are unusual among birds of prey in that they hunt in groups: with previous years' chicks hanging around to help out their parents. When hunting, several birds will fly ahead while another flushes prey forward towards them -- like the velociraptors of Jurassic Park. Their social nature and their intelligence make them ideal for human use; and they are now the species most widely used in western falconry.

These hawks, as well as peregrine falcons, are commonly used in management of public spaces to deter pigeons. Around London, for example, the birds have been used at St Pancras Station, St Pauls, Trafalgar square, and Westminster Abbey to deter pigeons during major events. Rufus and his colleagues will also be zipping around the olympic site. Rufus hit the headlines this year as he went missing from Wimbledon last weekend when he was stolen from a van in which he had been left overnight. Fortunately he was left, unharmed, with the RSPCA and is now back on duty.


Here's a song fittingly called Army of Birds by the  marvellous Gaggle whose album launch gig I am off to this evening.

And here is a song about tennis players (well, it's not about tennis players, but the title suggests it might be and it is bloody beautiful).

As I leave this post Murray is one set down four games apiece in the second set of the quarter final against Ferrer. I very much enjoyed the candour of one Spectator I saw interviewed in the coverage:

BBC reporter: "Do you think Andy Murray stands a chance this year"
Interviewee: "No"