About the complex sex lives of hermaphrodite snails, who may or may not have a phallus: to be sung to the tune of ‘Oh dear, what can the matter be? Three old ladies stuck in the lavat’ry…’
‘Dear, dear! What can the matter be?’
‘Oh dear! Two snails with aphally.’
‘See, dear – they’re hermaphroditidae.
Can they have fun at the Fair?’
(The aphallic snail puts its case.)
‘But I don’t need another, I’m father and mother.
No sexual behaviour’s an energy-saver.
A penis is silly, I don’t need a willy!
I have fun on my own at the fair.
Hey ho! We’re Bulinus truncatus.
It’s so! Our sex-life’s the greatest.
Ho ho! Cross-breeders or self-maters,
We all can have fun at the Fair.
(The phallic couple’s case)
We’re both sisters and brothers, we’re like two paired lovers.
We each can inseminate, phallus can penetrate,
Not so! I am dominant, penis is prominent.
So which has most fun at the Fair?
Ha ha! Our genetics are so complex.
Ooh ah! So too are our modes of sex.
Production of offspring is one of our main objects,
So our species can go to the Fair.
(The tetraploid’s lament)
With four sets of chromosomes, I’m host to schistosomes,
Humans would best avoid water near tetraploids.
A larva could bore in, through my unprotected skin –
Then I’d have no fun at the Fair.
Oh dear, this water’s too fast to drowse.
Help, dear, I just want to stay and browse.
Quick, dear! Stick your foot where the rock allows,
Or we’ll be washed away from the Fair.
(The survivor’s lament)
I’m male and I’m female, but I am a lonely snail —
No-one to talk or play, they’ve all been washed away.
I’m alive and I’ll thrive, and I hope my own eggs survive.
I’ll be joined by my kids at the Fair.
This piece of doggerel (it hardly qualifies as a poem!) comes from my novel Seaside Pleasures – and has some relevance to the story. One of the main characters is a malacologist/parasitologist …
The ‘singing snails’ are Bulinus truncatus, which are found in the shallow water at the edges of lakes in Africa.
These ‘tetraploid’ variants – they have 4 sets of chromosomes – are the intermediate hosts of an extremely debilitating disease in humans known as urinary bilharzia or schistosomiasis, caused by the parasitic worm Schistosoma haematobium. The male and female adult worms live in permanent copula in the blood vessels around the bladder; the female releases fertilised eggs, each of which has a spine on the egg-shell and gets pushed through the muscles of the bladder wall.
If the infected human pees into fresh water, the eggs hatch into tiny larvae, miracidia, which swim around until they find a snail; they burrow into the snail and undergo a complex multiplicative lifecycle inside it then burst out as another swimming stage, the cercariae, which can burrow in through a person’s skin. These migrate and undergo further development inside the human, finally ending up in the bladder wall.