#ricinulei

[vintagewildlife]

Ricinulei (Pseudocellus pelaezi) By: Sbordoni From: The Illustrated Encyclopedia of the Animal Kingdom 1968

[bestanimal]

Round 3 - Arachnida - Ricinulei

(Sources - 1, 2, 3, 4)

Order: Ricinulei

Common Name: “hooded tickspiders”

Families: 1 - Ricinoididae

Anatomy: "hood" (cucullus) can be raised and lowered over the head; no eyes; very thick exoskeleton; complex pedipalps with small pinchers which can be used to not only manipulate food but also bear many sensory structures, used as short-range sensory organs; the second pair of legs is longest and are used to feel ahead of the animal, similarly to antennae; in males, the third pair of legs are uniquely modified to form copulatory organs

Diet: smaller arthropods

Habitat: leaf-litter or caves in west-central Africa and the Americas (from Brazil to southern Texas)

Evolved in: Late Carboniferous

(source)

Do you have a favorite in Ricinulei?

One or more of my favorite animals is in Ricinulei

I love at least one or more of these animals

I like at least one or more of these animals

I am neutral about all of these animals

I dislike all of these animals

Voting ended onSep 11, 2025

Propaganda under the cut:

Living ricinuleids are typically about 5 to 10 millimetres (0.2 to 0.4 in) long, but the largest ricinuleid known to ever exist was the Late Carboniferous Curculioides bohemondi, with a body length of 21.77 mm (0.9 in).

Although living ricinuleids have no eyes, two pairs of lateral eyes can be seen in fossils and even living species retain light-sensitive areas of their exoskeleton in the same position.

The cucullus (“hood”) of ricinuleids is not only used to protect their head and eyes, but females will also use it to carry their single egg underneath the hood until it hatches. The young hatch as six-legged larvae, which later molt into their eight-legged adult forms.

Like many other arachnids, ricinuleids glow bright blue under UV light.

Ricinuleids are poorly studied, but most species appear to be social, which is rare for arachnids. Researchers have recorded novel interactions between individuals, other than mating, and the animals are often found in large congregations.

The position of ricinuleids within Arachnida has been contentious since their discovery. They were initially described as a bizarre suborder of harvestmen (Opiliones). Since then, they have received their own order, and been placed by different studies as the sister group of either Acari (mites and ticks), the extinct arachnid order Trigonotarbida, Xiphosura (horseshoe crabs), or Opiliones. Ricinuleids, however, don’t care about what we think they are or aren’t, and will continue doing whatever it is they’ve been doing since the Carboniferous.

[have-you-seen-this-animal]

Have you seen the Atewa hooded spider (Ricinoides atewa)?

I have now

Yes, in photos/videos

Yes, irl

I'm not sure

Voting ended onSep 7, 2025

The first image is of an adult, the second is of a nymph. This species is about 9.63 mm long, one of the largest ricinuleids.

[herpsandbirds]

Hooded Tick Spider (Cryptocellus goodnighti), family Ricinoididae, Costa Rica

Hooded Tick Spiders are not spiders, but are in a separate order of arachnids, the Ricinulei.

photograph by M. Hedin 

[dailybugfacts]

ricinulei🥺

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TODAY'S FACT IS

Did you know that Ricinulei is a relatively obscure order of small arachnids? Though no individual species has its own common name, the order as a whole is sometimes referred to as Hooded Tickspiders.

Yeah sure these little guys look cute, but what's really interesting to me about them is that they are considered a Lazarus taxon. That means that the order as a whole was present in the fossil record, disappeared for a substantial time, and came back. This usually happens in obscure, isolated, or extremely specific envrionments.

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Photo of Pseudocellis Pearsi by Rosa Fernandez and Gonzalo Giribet

[cuttledreams-bugs]

InsertAnInvert2024

February Theme - Relationships: Courtship

Week 5: Hooded Tickspider (Ricinulei)

Between the long feeler legs, interlocking body segments, protective cucullus hood, and cool shades of red, these guys jumped right up to some of my fav arachnids. I'm in love~

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Interested in learning more about the invertebrate animals around us? Join into the year-long InsertAnInvert event organized by Franzanth, where every week a new animal is spotlighted following each monthly theme! Draw unique animals, read up on cool facts, or just follow the tag online to see a lot of cool artwork.

Prompt List: https://bsky.app/profile/franzanth.bsky.social/post/3khyob3xn742q

[onenicebugperday]

Hooded tickspiders (Ricinulei) are an order of small, predatory arachnids that feed on other arthropods. Despite the name, they are neither true spiders nor ticks. First described from fossils, these arachnids were once thought to be extinct, but more than 70 living species have since been described worldwide.

They are notable for their hood (or cucullus) which can be raised and lowered over the head; when lowered, it covers the mouth and chelicerae entirely. Hooded tickspiders have no eyes, but do have light-sensitive areas of cuticle on their exoskeleton.

After receiving a spermatophore from a male, the female will carry a single fertilized egg under her hood until it hatches.

Photos 1-3 by cesarfavacho, 4 by M. Hedin, 5 by b_akeret, 6-7 by alex-valmond, 8 by aztekium_tutor, and 9 by braytonidae

[bowelflies]

I found a “weird” spider in my house. But it wasn’t a spider at all. It was a hooded tick spider. I’ve never seen one in person before. What exactly are they? I know they’re another arachnid order. But normally I only see you know: true spiders, opiliones, book scorpions, those little blind whip scorpions in the potting soil, true scorpions, camel spiders, predatory mites, ok a lot of arachnids. But not the hooded tick spiders. So I know next to nothing about them.

wow! i’ve only ever seen one once, in Nicaragua, since they’re a super rare, strictly tropical group except for like a single species described from the rio grande valley in texas.

i’m afraid i wouldn’t be able to tell you anything about them that you couldn’t get from perusing the wikipedia article. the last time i thought about them was about a year ago when there was an uproar in the greater entomology community after someone published a paper purporting that horseshoe crabs are a sister group to hooded tick spiders based on DNA evidence. personally i think that’s total horse shit (horseshoe crab shit, even) and there’s a ton of ways that DNA-inferred phylogenetics can go wrong and molecular phylogeny dogmatists are deluded BUT ANYWAY that was a fun week of people yelling about arachnids.

good job on spotting a rare pet! send me pics!

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