the wasp-mimic mantisfly (Climaciella brunnea) is not only one of the coolest bugs out there but can also be surprisingly calm and friendly, at least if you charm it with the offering of a delicious blood-filled mosquito
(Massachusetts, 7/3/23)
did you know?
you love chubby springtails.
you love them. you have to.
(likely Sensillanura sp., Vitronura giselae and Neanura muscorum)
It's big, it's strong, its scaly, it's this week's Wet Beast Wednesday topic! An arapaima, also known as a pirarucu or paiche, is any of four species of fish in the genus Arapaima in the order of bony-tongued fish. There is som ongoing debate about the classification of the species, so to keep thing simple, I'm going to use the most common species names of Arapaima gigas (the type species and most well known, and the one with the most confusion about its classification), Arapaima agassizii, Arapaima leptosoma, and Arapaima mapae. Because A. gigas is the most well-studied of the species, unless I say otherwise you can assume everything I say in this post applies to it.
(image: an arapaima)
Arapaimas are bony fish that retain several primitive traits, causing them to sometimes be identified as "living fossils". They are most notable for their size, with A. gigas being a contender for the largest freshwater fish in the world. The maximum recorded size for one was 3.7 meters (10 ft) and 200 kg (400 lbs), but most get to around 2 meters (6.6 ft) long and 200 kg (440 lbs). That average length is decreasing as overfishing of the largest individuals is resulting in a selective pressure for smaller sizes. In addition to their size, they are extremely strong and can move fast if needed. Arapaima are fully capable of leaping out of the water if disturbed or they feel their current pond in unsuitable. Because of their strength, specimens in captivity must be handled with care as they can easy break bones if they slap someone. They live in rivers and lakes in South America, where they are often the top predators.
(image: several anglers with an arapaima)
Arapaimas are obligate air-breathers and will drown if they can't get to the surface to breathe. This is accomplished with a specialized swim bladder. The swim bladder is filled with highly vascularized tissue, letting it act like a lung. This pseudo-lung opens into the mouth using a modified gill arch known as the labyrinth organ. Arapaima gills are too small to sustain them, but they can supplement their oxygen intake with the gills. Juveniles are born exclusively using their gills and transition into air-breathers shortly after hatching. Arapaimas can survive up to a full day out of the water. They typically surface to gulp in air every 15-20 minutes. Breathing makes a loud gulping sound that anglers use to target them.
(image: an arapaima at the surface)
Because of their ability to breathe air, arapaimas are top predators in low-oxygen environments. Non-air breathing fish are forced to slow down in water with low levels of dissolved oxygen as they can't get enough oxygen through their gills. Since Arapaimas breathe air, they can easily chase down lethargic smaller fish. They are especially potent predators during the low season, when water levels lower. A combination of rotting vegetation reducing oxygen levels and ponds getting cut off from rivers and losing a supply of oxygen lets the arapaima reign supreme. Arapaimas are primarily predators that feed on smaller fish, though they will hunt other types of animals and eat fruits and seeds. Even land animals aren't safe as arapaimas have been known to launch themselves out of the water to catch animals near the shore. A combination of sharp teeth and their bony tongues are used to debilitate prey.
(image: an arapaima with its mouth open)
Not content with powerleveling their attack stat, arapaimas also have excellent defense. Their scales have been compared to bullet proof vests. Each has a hard, mineralized outer layer over multiple layers of collagen fibers. These layers are all oriented at an angle to each other to provide extra strength. This orientation of layers is called a Bouligand-type arrangement and is similar to how plywood is assembled. The harder outer layers and flexible inner layers work together to allow for both strength and flexibility. These scales help provide protection form large predators such as caiman and small threats like biting piranha. They also like provide protection from other arapaima, as the fish are aggressive and will fight each other.
(image: a diagram showing the composition of arapaima scales. source)
You probably wouldn't expect a swimming tank of an animal to be a good parent, but you'd be wrong. Arapaimas work together in mated pairs to build nests for their eggs, then cooperate to guard the nest. Once the eggs hatch, the male will practice mouth brooding, keeping his young safe in his mouth. The female will also help by patrolling the area around the male to ward off predators. They secrete pheromones from their heads to ensure the young don't swim too far away. Eggs are laid either in in the low season or as water levels are starting to rise, ensuring that the young become independent during the high season.
(Image: baby arapaimas)
Arapaima are classified as "data deficient" by the IUCN. This means there isn't enough data to properly assess their conservation needs. They are known to be threatened by overfishing. Arapaima make up a large part of the diet of many South American populations. Habitat loss and pollution are also believed to threaten them. They have been introduced to many areas out of their native range and are an invasive species in placed like Florida, Malaysia, and India.
Does anyone else remember these cards? (image: the arapaima card from Weird n' Wild Creatures)
an eastern red centipede (Scolopocryptops sexspinosus) watching over her little donut babies
(Florida, 3/30/22)
Open Your Home to the Common House Centipede
A common sight in homes throughout Europe, Asia, the Americas, and Australia the common house centipede (Scutigera coleoptrata) is a medium-sized species of centipede originally from the Mediterranean. In the wild, they prefer grasslands and deciduous forests where they can hide under rocks, logs, or leaf litter. These insects have also adapted well to urban development, and are frequently found in basements, bathrooms, and garages, as well as gardens and compost piles.
Like other centipedes, the common house centipede has less than 100 legs; in fact, they only have 15 pairs, with the front pair used only for holding prey or fending off threats. All those legs let the common house centipede move up to 0.4 meters per second (1.3 ft/s) over a variety of surfaces, including walls and ceilings. The actual body of S. coleoptrata is only 25 to 35 mm (1.0 to 1.4 in) long, but the antennae are often as long as the body which can give this insect a much larger appearance. However, they can be hard to spot, especially in their natural environments; their tan and dark brown coloration allows them to blend in seamlessly to surrounding vegetation.
Though they pose little threat to humans, house centipedes are predatory. Their primary food source is other arthropods, including cockroaches, silverfish, bed bugs, ticks, ants, and insect larvae. S. coleoptrata is a nocturnal hunter, and uses its long antennae to track scents and tactile information. Their compound eyes, unusual for centipede species, can distinguish daylight and ultraviolet light but is generally used as a secondary sensory organ. When they do find prey, house centipedes inject a venom which can be lethal in smaller organisms, but is largely harmless to larger animals. This makes them important pest controllers. In the wild, house centipedes are the common prey of rodents, amphibians, birds, and other insects.
The mating season for S. coleoptrata begins in the spring, when males and females release pheromones that they can use to find each other. Once located, the male spins a silk pad in which he places his sperm for the female to collect. She then lays fertilized eggs in warm, moist soil in clutches of 60-150. These eggs incubate for about a month, and the young emerge with only four pairs of legs. Over the next three years, juvenile house centipedes molt 7 times, each time gaining new pairs of legs. After they grow their last pair of legs, immature house centipedes molt an additional 3 times, at which time they become sexually mature. If they can avoid predation, individuals can live up to 7 years in the wild.
Conservation status: The common house centipede has not been evaluated by the IUCN, as it is relatively common both in the wild and in urban areas. Although they have been introduced to areas outside their native range, no detrimental environmental effects have been associated with their spread.
If you like what I do, consider leaving a tip or buying me a ko-fi!
Photos
I was soundly defeated by this large Gryllotalpa nymphicus mole cricket I picked up in Singapore. with stunning speed and strength, she deposited a sticky goo on my hands, pried my fingers apart, and gave me a vicious bite before disappearing beneath a pile of rotten wood (where she then posed nicely for photos)
never met a gryllotalpid before, and wasn’t expecting the viscous slime or the bite! I did know they’re incredibly strong though, and this smaller (much less nasty) male seen later displays mole crickets’ beefy digging arms:
the videos I’ve seen of smaller US species just bumbling about and trying to burrow in peoples hands made me expect a charming dirt puppy. the big female ran under my shoe at one point and I could actually feel her lifting me up from the road. I suppose I was trying not to squish her, but still! incredibly powerful beasts
the top ones, are terrestrial crustaceans, ie have gills, require sufficiently watery air to breathe, etc while on the bottom, those are insects like you’d expect, and the two are NOT RELATED!
i love rollie pollies and evolution does too
millipedes are myriapods, and insects are probably closer related to crustaceans like isopods than millipedes + centipedes!
being able to roll into a ball is just a recurring phenomenon among earth life—there’s cockroaches (Perisphaerus), various beetles, armadillos, and trilobites might’ve been the first to try it. even among the isopods, being able to conglobate probably evolved at least five times, and probably far more than that.
here’s Perisphaerus—a female.
male perisphaerine cockroaches just look normal. Pseudoglomeris is a less pilly related genus, with a perfectly spherical body exchanged for metallic shine
Sharpshooter molting, Oncometopia sp., Cicadellidae (leafhoppers)
Photographed in Costa Rica by fedecrc
Normal coloration on a similar species:
Oncometopia clarior by slowswakey
Globular springtail, Bourletiella arvalis, Bourletiellidae, Collembola, Hexapoda
Springtails are a species of omnivorous, wingless hexapod (six-legged arthropods but not insects) found throughout the world in most habitats, especially in damp soil where they help with nutrient recycling. As their name implies, globular springtails are much more rounded than the usual long-bodied springtails. This species, Bourletiella arvalis, is found in North America and Europe.
Photos 1-2 by nomolosx, 3 by alexis_orion, 4 by keimwj, 5 by berkshirenaturalist, 6 by mrmacro, 7-8 by robidium, and gifs 9-10 by sloppydemon
Thank u for letting me know that the sea spider genus Dodecalopoda can have TWELVE legs instead of the usual eight and also it’s one of the abyssal groups that gets huge :D
Fun fact: Green forester moths (Adscita statices) aren't always green— on cool nights they become a rusty orange, then change back to blue-green in the morning.
This color change is possible due to the unique structure of some specialized wing scales:
The layers of tiny air pockets in these scales absorb water vapor from dewy night air, changing the way the light refracts:
Their color change reverses as the wing scales dry out in the sun:
Top photos: Joachim Wimmer and Linda Kjær-Thomsen. Everything else from Wilts BD, Mothander K, Kelber A. 2019 Humidity-dependent colour change in the green forester moth, Adscita statices. (Photos cropped/relabeled for clarity)
