SciBlogs

Posts Tagged animal diversity

see-through creatures Alison Campbell May 08

No Comments

This is a ‘glass frog’ (image from National Geographic):

It’s one of a number of transparent or translucent creatures featured on the National Geographic’s "Weird & Wild" blog. (Actually I take issue with the Monarch butterfly image there, as strictly speaking we’re seeing a transparent pupal case; the butterfly inside is definitely not see-through.)

Glass frogs (Hyalinobatrachium pellucidum) are on the ICUN’s ‘red’ list as an endangered species, with habitat destruction the likely cause. However, if chitrid fungi are introduced to the frog’s limited range  - they’re recorded from only five locations on the Amazonian slopes of the Andes in Ecuador – then the population will likely decline even faster (always supposing this particular pathogen isn’t already there). These delightful little frogs are apparently about the size of a fingernail, & their translucency is due to a lack of pigment in the skin. Not only can you see the air-filled lungs, the red threads that are blood vessels, and the heart with some of the major arterial arches clearly visible – you can also see the animal’s skeleton.

And that reminds me: we were talking in class the other day about gastric-brooding frogs & one of the students said they’d heard that this species had been cloned. An intriguing possibility – I must go off & look into it!

 

true facts… Alison Campbell Apr 26

No Comments

 OK, you could argue that you can’t have a ‘false’ fact :) But that aside – I was recently introduced to this little gem of a video, True Facts About The Chameleon. Nice little sound-bites of information, rather lovely images – and the narrator’s voice-over had me in stitches. (But he’ll never replace Sir David Attenborough!)

Enjoy! (I’m going to sit & see what else he has to say about praying mantids: I’ve already heard the bits about having puppydog eyes and complex mouthparts that include "a moustache beneath [its] mouth – made of fingers" – a novel take on the animal’s lower ‘jaw’.)

attack of the zombie snails Alison Campbell Mar 25

No Comments

Honestly, sometimes I think the zombie apocalypse is already here. Certainly zombies seem to be flavour of the month (& whatever friends say, I still can’t bring myself to watch Walking Dead). And I’ve written about them myself: well, the insect variety, anyway.

But our developing understanding of how parasites ‘zombify’ their hosts has been developing since well before the latest iteration of human zombies grabbed the popular imagination. I was reminded of this when I saw the video below (in all its over-the-top hyperbolic glory), for I was first introduced to the concept of zombie snails years & years ago by one of David Attenborough’s TV programs**. (According to my aging memory, it would have been an episode of Life on Earth.)

The parasite involved here is a flatworm (strictly speaking, a member of the branch of Platyhelminthes known as flukes) called Leucochloridium paradoxum. It has the delightful common name “green-banded broodsac”, which is a pretty accurate description of its appearance.

Flukes have a fairly complicated life cycle involving multiple hosts and L,paradoxum is no exception: eggs hatch into miracidia, and each miracidium subequently develops into a sporocyst. Each sporocyst contains large numbers of cercariae, which is where the ‘broodsac’ name comes from. In this state they move through the snail’s body to its ocular tentacles, where their bright colours & movement show through the thin skin of the eyestalks. Apparently, if you’re a bird, this looks like a caterpillar… Anyway, once ingested by a bird, the cercariae mature into adults, which reproduce and the whole cycle begins once more.

Where does the mind control part come in? Well, your average snail doesn’t usually spend a lot of time out in the open – such behaviour can make one rather too visible to predators. But instead of their normal photophobic behaviour, infected snails come out in the open, often climbing up grass stems or out onto branches. Combined with the flashy tentacular display – which doesn’t occur in the dark – this makes them easily visible, & easy prey. (Having said that, I do wonder whether this is truly mind control: after all, having a parasite stuffed up your eyestalk must impair one’s ability to detect ambient light intensity.)

 

** And in ‘reading’ up for this post, I see that the wonderful Sir David also covered the zombie ants:

 

artistry Alison Campbell Feb 13

No Comments

We are in full enrolment mode at the moment – for some reason a lot of students have left re-enrolling &/or seeking advice until the Very Last Moment – so I have little time for serious blogging. (It’s always the same at this time of year, only this year more of the same.) But I still have an eye for lovely biological images. So how’s this for a combination of artistry and science?

They’re from the Science is Awesome FB page:

They’re the work of Italian artist Guido Daniele, who uses hands as his canvas. One hand can take up to ten hours.

Ah, well, back to the grindstone.Your turn, Grant :)

where’s pooh? Alison Campbell Jan 30

No Comments

I stumbled across this image of Helicocranchia pfefferri a little while ago – easy to see why this little cephalopod is called the ‘piglet squid’!

Image (c) Cabrillo Marine Aquarium.

The Cabrillo Marine Aquarium’s news release tells us that these little animals (“about the size of a small avocado”) are a deep-water species with a global distribution. The piglet’s ‘smile’ is actually a row of chromatophores, or pigmented organs, more of which dot the transparent body wall – so transparent, in fact, that you can see some of the animal’s internal organs. And each of its eyes has a photophore (a light-producing organ) set beneath it.

For some strange reason I am also reminded of the dumbo octopus (Grimpoteuthis sp.).

 

 

 

 

 

 

 

 

 

is this fish evil? Alison Campbell Dec 03

5 Comments

On Facebook a while back, I noticed a post with an image of a fish under the caption, “Is this fish evil?” What with the way FB stuff rapidly disappears down the plughole timeline to the past I couldn’t find that post again (where’s Dr Who when you really need him?), but this is that image (and thank you, Mr Google):

It’s a deep-sea viperfish, one of a gallery of rather alarming-looking creatures included in a post at Deep Sea News. The image, & FB post, caught my attention because of the use of ‘evil’ alongside the word ‘fish’. After all, the viperfish, like anglerfish & the truly alarming-looking stoplight loosejaw, are just fish, doing what fish gotta do. So why do people tend to characterise these animals as evil? After all, as the writer at Deep Sea News points out, they pose no threat to us, for all their Halloween appearance.

Part of it seems to be the dark colour and angular shape (Darth Vader, anyone?): both appear to trigger a fear response in humans. This is understandable enough for things like dangerous spiders, but deep-sea fish that we’ll never meet. Is there some sort of hardwired response to a particular set of characteristics that screams ‘danger! (danger, Will Robinson!) when we see them?

I suspect this is partially the case, but that there’s also an element of learning involved. Back in the days when I was working at Massey, I was privileged to be able to take a couple of Mahoenui giant weta out on trips to schools. The children’s responses were fascinating. Children from kindergartens, & early primary school, were absolutely fascinated – please could they have the weta sitting on them? They crowded in, got close & personal (& were really really careful to be slow & gentle around the animals). But secondary students were more likely to have an ‘eeewwww’ response. As did many of the kindy parents, who were far more likely to go ‘oh yuck’ rather than ‘ooh that’s wonderful’. Learning? Yes, I think so.

Also, there is surely more to the initial caption than this. What’s the difference between simple danger, & the suite of traits that humans label ‘evil’? After all, we recognise the danger in a lion or tiger (or bear), but you don’t often see them with the ‘evil’ label attached.

stingray x-ray Alison Campbell Nov 21

1 Comment

Another in the occasional series of rather lovely biological images: an x-ray of a stingray (Heliotrygon sp.)

(from NatGeo, via Pharyngula)

The genus name means ‘sun stingray’, a name that was given for the way that the cartilage fibres that support its body (like sharks, stingrays have a skeleton that’s based on cartilage, unlike the hard, ossified skeleton of (adult) humans).

Another cool thing about this image is that you can clearly see that this stingray is, in fact, stingless!

sweet memories Alison Campbell Oct 04

No Comments

I’ve just found a new blog that is a must-follow: Becky Crew’s Running Ponies.

Run, don’t walk, over there – and read wondrous posts such as her discussion of a study that found chocolate** appears to enhance snails’ ability to form lasting memories. I wonder what will happen to chocolate sales at the uni shop, when I share this one with my students…

Also, boogie-woogie aphids!

** actually, a chemical found in chocolate; the poor snails missed out on the whole mouthfeel side of the experience :)

traumatic insemination? ooh that sounds painful! Alison Campbell Sep 26

No Comments

Bedbugs. One of the critters that I’d prefer not to encounter on my travels. They come out at night and bite sleeping humans (& other animals), retreating during the day to their dark hideaways, often in cracks in furniture, walls, or floors. This sounds very insanitary but the species that bites humans, Cimex lectularius, isn’t generally regarded as a disease vector, and while a review published in 1963 found that bed bugs can carry a range of pathogens, the author also concluded that there was no scientific evidence of actual transmission of disease. At least one recent research study found that Rickettsia could survive in the insects’ blood for several days after infection, but again noted no evidence that the pathogen was spread in the bugs’ bites.

Now, I know that a bug’s gotta do what a bug’s gotta do. But even when it comes to their love lives, bed bugs are just not that, well, nice. For mating in the African bat bug (a relative of C.lectularius) sounds more like open warfare than a tender meeting of the sexes.

In this, and in other Cimex species (including lectularius), male bugs don’t mess around. Rather than find the female’s genitalia & follow a more normal route, the male simply stabs his penis into his mate’s abdomen. Ouch! Traumatic insemination, indeed. His sperm are injected into her blood-filled body cavity (insects have an open circulatory system) and make their way thence to her ovaries. Not only is the female physically damaged by this act, but it must also open the door to infection by pathogens. It turns out that males are also susceptible to damage as they are not too fussy about who they mate with, and at times another male ‘will do’.

The risk of harm is not trivial, and so individuals with any trait that might minimise the harm is going to be at a selective advantage (& if that trait has a heritable component, the underlying alleles will spread through the population’s gene pool). The result is the evolution of ‘paragenitals’ in both males and females: structures described as ‘extra genital funnel[s]‘ (Dolgin, 2007) that are easy to access and increase the odds that matings will be in that spot rather than randomly all over the abdomen. What’s more, the male’s penis enters a cavity lined with immune cells (like all animals, insects have an innate immune system), which reduces the odds that the mating partner will pick up an infection.

There is, of course, a disadvantage to a male bug in looking like a female – more males may start to hit on him. Consequently males’ paragenitals differ from females’ in that they are more open (their funnel is a different shape). But the story doesn’t stop there. It turns out that at least some female bat bugs’ paragenitals look more like those of the males – and that this deception works: counting the scars on their abdomens, & comparing the results with the scores for more girly girls, showed that male-like females had suffered fewer of those random mating stabbings.

I shall let the reporter at Evolution (on Facebook, where I first spotted this story) have the last word:

If you’re having trouble envisioning this cross-dressing insanity, picture this – the males are dressed like girls, and the girls dressed like guys who are dressed like girls, and everyone’s doing this to avoid sex.

(Avoid it as much as possible. But not completely – for that route would lead to the oblivion of extinction.)
E.Dolgin (2007) Bug sexual warfare drives gender bender: African bat bugs have two types of female genitalia Nature (published online 20 September 2007) doi: 10.1038/news070917-7

 

an ambulant toupee? Alison Campbell Sep 22

2 Comments

No, it’s a megalopygid moth caterpillar (via Science Alert on Facebook).

Image: Rainforest Expeditions (on Facebook)

Megalopygids are also called ‘flannel moths’ (you can see images of both adults and larvae here - the larvae are quite diverse in appearance). I do wonder, after looking at this adult, if they aren’t related to the poodle moth I shared with you a few posts ago.

Apparently the larvae, which are 2-3cm long, are called ‘puss caterpillars‘, presumably because the long hairs that cover their bodies make them look vaguely (very vaguely!) cat-like**. But you wouldn’t want to stroke them. Hidden in all that seemingly soft fluffiness are spines tipped with venom that causes a burning pain, & inflammation that can last for several days – with the nastiest species, in a worst-case scenario the victim may go into shock. So you’d want to restrain the urge to touch, if you came across one (in the southern US, Mexico, or Central America).

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

** I’m afraid I don’t think ‘cat’ when I see that image; it reminds me more of a certain millionaire’s hairpiece…

« Older Entries

Network-wide options by YD - Freelance Wordpress Developer