hi everybody, welcome to another excellent episode of Weird Biology! I definitely had some trouble picking an animal for this week.
“bunjy,” you say, wringing your hands dolefully, “it’s been a while since you did an invertebrate, maybe do one of those”
well, you couldn’t be more right!
so without further ado, I’d like to introduce you to a good, soft boy.
a good, good boy!
“oh,” you say dejectedly, still wringing your hands, “worm?”
okay first off, how dare you, worms are great. second, they aren’t even worms, despite the name. Velvet Worms are actually panarthropods, most closely related to arthropods and tardigrades (though they look more like a multi-legged velveteen slap bracelet). Velvet Worms consist of about 200 known species in their very own adorable phylum, Onychophora.
the panarthropods first wriggled into existence all the way back during the Cambrian Period, 540 or so million years ago (you know, plus or minus a few million). they have changed very little since then, making the transition onto land but keeping the adorable alien-teddy-bear look.
if it ain’t broke, don’t fix it.
Velvet Worms are found across the tropics and southern hemisphere, and reach lengths of 0.2 to 8 inches depending on species. they come in many colors, though Red Flavor is probably the most well-known. they are velvety squooshy soft to the touch, and have between 13 and 43 pairs of adorable tiny feets (depending on species). also, they don’t have a skeleton and operate entirely by hydraulics.
unlike vertebrates like you, the Velvet Worm moves by rapidly inflating and deflating parts of their squishy squashy bodies with internal fluid. just imagine that they’re made entirely of water balloons that can wiggle awkwardly in any direction.
wobble wibble wobble.
given their soft wobbly balloony body and adorable face, it may surprise you to learn that Velvet Worms are actually voracious predators. they are efficient and successful killers, mainly eating insects and other small creatures.
Velvet Worms hunt by sneaking up on possible prey and papping it gently with their retractable antenna to see if it is good for eating. which is, uh, not the stealthiest option. I mean, can you imagine if every time you wanted a snack you had to walk up to it like “LET ME JUST RUB MY HANDS ALL OVER YOU TO SEE IF YOU’RE EDIBLE, HOLD STILL PLEASE”. it seems to work okay for the Velvet Worm, though.
but anyway once it has the prey lined up in its sights, the Velvet Worm unleashes its secret weapon.
that’s right, the Velvet Worm turns its whole face into a high-powered hose that jets a double stream of slime up to a foot away! it’s the super-soaker of nightmares. once the target is slimed, it ain’t goin nowhere. the slime rapidly hardens into a solid mess, literally gluing the victim in place.
it’s the most badass special attack of any invertebrate short of the Bombardier Beetle.
what? how could I not be excited about what is basically a real-life Pokemon move?
moving on. after the Velvet Worm has immobilized its prey, it unleashes its even more secret weapon. hidden in that soft gooshy adorable face are a pair of razor-sharp nightmare jaws and a powerful dissolving enzyme. the Velvet Worm uses them both on its victim, making quick work of prey.
some species of Velvet Worms will even hunt cooperatively, using their x2 Combined Slime Cannon to bring down large prey they wouldn’t be able to handle separately. these hunting parties are led by a female warlord (wormlord?) who will eat her fill before the other Velvet Worms are allowed to feast.
cold, merciless and completely adorable.
this group hunting behavior shows that Velvet Worms have surprisingly complex behaviors. but it’s still got nothing on their reproductive strategy, which has been best described as “yikes”.
after a brief courtship that varies between species, the male Velvet Worm just kind of plops a packet of sperm onto the female’s back and leaves. which, not very romantic, but okay. but then the female then proceeds to dissolve some of her skin and absorb the sperm into her bloodstream. holy shit. several months later, the female gives birth to a new crop of wriggly babies. it’s a functional strategy, but probably leads to an interesting domestic life.
"don’t sass back at me mister, I dissolved my skin for you!”
though Velvet Worms in all their splendid weirdness are still commonly found across the world, we don’t actually know how they’re doing ecologically because they aren’t studied very often. we do know that Velvet Worms are threatened by habitat destruction and human expansion, and scientists suspect that individual species range from near threatened to critically endangered. this is not allowed.
conservation programs need to be enacted for these good soft boys, and soon. we hope that Velvet Worms and their many many soft gentle feet stick around for a long time to come.
thanks for reading! you can find the rest of the Weird Biology series here.
So today while playing New Horizon, I caught a familiar looking fish that I didn't really know much about.
Though called the Napoleonfish in the game, I know it as the Humphead Wrasse.
According to Blathers (that lovable owl) this fish is endangered, but doesn't really give much more information than that. It really left me, a person fascinated by the outside world, wanting more than just that measly bit of fact and boy does the game not do this fish justice.
Found in the coral reefs of the indo Pacific region, the humphead wrasse is a very large fish, growing up to 2 meters long.
They are a powerful fish, with strong teeth, able to break down clams and mollusks with little to no effort.
So, if this fish is so powerful, why is it endangered?
Well there are multiple reasons, but one reason that stood out to me is that not a lot of people know about this fish. The lack of awareness of this species. So I've decided to do my part and bring awareness to this fish.
This animal is classified as endangered, however it is also considered to be "conservation dependent" meaning that by this point it is a species that relies on our help. Human help.
So why care about this animal? Fantastic question. As mentioned earlier, the humphead wrasse eats shellfish and other hard to eat animals, but the most notable thing that this fish eats is the dreaded crown-of-thorns starfish.
This invertebrate feeds on coral reefs, and with very few predators to prevent it from over populating, these starfish can strip entire reefs of it's coral which is vital to all life in the ocean.
The humphead wrasse is one of the few animals that can withstand the crown-of-thorns' toxins, and can keep the population in check.
But how can we help more?
Educate yourself more about the species.
Support the WWF, as they have a program that helps release humphead wrasse back into the wild.
Do not fish for this animal. If you catch it by accident, let it go.
And finally respect this amazing animal for it's majesty and power.
There’s actually a couple of reasons we think cuttlefish evolved such unusual shaped pupils.
First, the W-shape helps them to balance out the uneven light levels in their habitat. Cuttlefish live in shallow areas, so there’s quite a lot of light at the top of their vision, but it becomes dimmer pretty quickly further down, so they need to deal with a fairly wide range of light intensities at the same time.
It’s a little difficult to explain, but basically the combination of horizontal and vertical oriented slits in the pupil result in an overall more even level of illumination across the retina, reducing the contrast between the brightest and darkest parts of the scene. This paper goes more into detail if you want to read it.
It is also thought that the W-shaped pupil might allow them to distinguish colour, despite being “colourblind” by our standards (they only possess one type of cone cell, whereas we have three).
Wide pupils let light in from many directions, but this scattering effect means their vision is subject to more chromatic aberration - the colourful “fringes” you get around objects when your vision is blurry, and also in photographs when you use a wider aperture. However, some scientists have theorised that they may be able to use what is usually considered a visual flaw as a way to discern colour in a completely different manner to any known animal.
According to this theory, cuttlefish (as well as squid and octopus, which have similar U-shaped pupils) distinguish colour by the relative focus of different wavelengths of light on their retina, which is accentuated by the increased amount of chromatic blur they get from their wide pupils. This idea is still theoretical, but it has been shown in a computer model. If it’s true, it would go long way to explaining the apparent paradox of cephalopods being colourblind and yet somehow able to undergo accurate colour changes to camouflage or mimic other creatures.
Did you know butterflies weren’t the first insects to look like butterflies?
Lepidopterans (the group of insects containing moths and butterflies) have been around since the Late Triassic -- but it wasn’t until the diversification of flowering plants during the Cretaceous that recognizable moths would have evolved, and true butterflies didn’t actually appear until the early Cenozoic.
Before then, back in the mid-Jurassic about 165 million years ago, a completely different group of insects convergently evolved remarkably butterfly-like features such as large colorful scaled wings and long sucking proboscises.
Known as the kalligrammatids, these insects were giant members of the lacewing group, related to modern forms like antlions and owlflies. But unlike their predatory relatives the kalligrammatids were specialized pollinators, possibly having a mutualistic relationship with the flower-like cones of bennettitales or the pollination drops of some types of conifers. They seem to have originated in China and were found across Asia and Europe by the Late Jurassic, but a few fossils from South America suggest they were even more widespread and may just have a poor fossil record.
They reached wingspans of up to 16cm (~6″), comparable to some of the largest modern butterflies, and often sported conspicuous anti-predator markings on their wings such as stripes and eyespots -- so it’s not surprising that they’re often nicknamed the “butterflies of the Jurassic”.
Rather ironically, the extinction of the kalligrammatids was probably linked to the rise of the flowering plants that the true butterflies would later be so dependent on. As flowers diversified and plants like the bennettitales declined, the kalligrammatids dwindled and disappeared, with the last known fossil record coming from the mid-Cretaceous of Brazil about 113 million years ago.
But while they were around, I do wonder if they also exhibited some similar behaviors -- such as mud-puddling for extra nutrients, and specifically the habit of drinking the tears of larger animals that we see in some species. Perhaps some non-avian dinosaurs like this Dilong occasionally put up with kalligrammatids sitting on their faces!
Why does the “cockeye” squid have a teeny tiny eye, and a giant green eye?
I’m so glad someone asked this - the cockeyed squid is one of my favourite molluscs for this exact reason. Here’s what they look like, for those who don’t know:
Cockeyed squid is actually a genus (Histioteuthis) that comprises quite a few species, including the one pictured above which is known by the adorable name, strawberry squid (Histioteuthis heteropsis), but they all have the famous odd-sized eyes - something that’s not seen in any other bilaterally symmetrical animal.
The reason for this is each of their eyes is adapted for a different type of vision. Cockeyed squid live in the mesoplegaic (or twilight) zone where sunlight is almost non-existent, and they generally float like in the picture above, with their large left eye facing slightly upwards, and their smaller right eye facing downwards.
The role of the fairly normal-looking right eye is to pick up up the bright bioluminescence of creatures in the dark below them. Their left eye, however, is specially adapted to break the counter-illumination of creatures swimming above them. Counter-illumination is a strategy adopted by many creatures in the deep sea, where they illuminate the underside of their bodies just enough to “counter” their silhouette made by the small amount sunlight coming from above. The squid’s large eye sees past this as it is very sensitive to light, and the greenish-yellow lens helps to filter out the sunlight, making the creatures stand out.
This article from MBARI goes into a bit more depth
These are scale worms - a recently discovered species that inhabits whalefalls and hydrothermal vents. While undeniably gorgeous it has also been observed that these guys will actively fight each other for resources; the arrows in the top photo indicate missing chunks of the scale plates, though damage is even more noticeable on the bottom photo. I got the pics from MBARI, check them out for more info, or @RebeccaRHelm on Twitter!
I’ve always wanted to see the sea lettuce slug (I’ve even crocheted it!) and I finally did!!!!! I saw several much larger ones snorkeling and this little one in a tide pool. They are even more beautiful than you could ever imagine!