Diagram of spider anatomy

Arachnews Glossary

a pesticide that kills mites and ticks.
a group of arachnids known as tailless whipscorpions or whip spiders. Adapted for life in caves and crevices, they are thin and flat, have long, clawlike pedipalps, and have turned their front pair of legs into thin whiplike antennae which they use to feel around in the dark. They don’t make venom or silk and are harmless to humans. You can put them on your face.
the group of spider families that includes pretty much any ordinary spider — orbweavers, wolf spiders, jumping spiders, sac spiders, etc. — except tarantulas and other mygalomorphs. You’ll sometimes hear araneomorphs called “true spiders” (though likely not by us). Araneomorphs tend to be smaller and shorter-lived, and their fangs swing in towards each other, like tweezers or scissor blades.
tree-dwelling, as opposed to terrestrial (land-dwelling) and fossorial (burrow-dwelling).
behavioural ecology
a field of science that asks (1) what are animals doing? (2) why? and (3) how are (1) and (2) affected by the animal’s interactions with its environment and other animals?
a group of organisms made up of an ancestor and all of its descendants. This explanation may be helpful.
a kind of silk that is tangly rather than sticky. Spiders make tangles in their silk by teasing it out with a comb (called the cribellum) on their back legs. The first araneomorphs made cribellate silk, but many of their descendants switched to sticky silk (ecribelllate, “lacking a cribellum”).
killing skin tissue. I. e., gnarly sores. Google at your peril.
a dormant state, kind of like hibernation. Arthropods can enter diapause seasonally, in response to environmental conditions, or as part of their life cycle.
DNA barcoding
identifying an organism by comparing a short, distinctive bit of its DNA to a reference library of samples from many species. There are very few spider barcodes.
the “back” side. In animals like insects and spiders, it’s their top side. See ventral.
a spider from the family Selenopidae, also called “moon-eyed spiders” because their eyes are arranged in a crescent.
a group of organisms within a species that share a haplotype.
a set of certain variations in DNA that are (almost) always inherited together. Since these variations are inherited together, individuals that share a haplotype (that is, are in the same haplogroup) are likely to be related to each other.
short for “harvestperson”, arachnids from the order Opiliones. Also known as “harvestmen” and “daddy-long-legs”. Note: I am literally the only one who calls them this. I’m trying to make it a thing.
arthropod “blood”. It uses copper molecules to carry oxygen, unlike our blood, which uses iron.
a comprehensive list (“-ome”) of all of the types of bacteria (“microbi-”), along with how many of each type, in a specified location.
micro-computed tomography
using X-rays to scan something one small slice at a time, then putting all the slices together to make a 3D model. Just like a CT scan, but smaller.
the powerhouse of the cell.
the group of spider families that includes tarantulas, trapdoor spiders, and other long-lived, chonky spiders. Their fangs move up-and-down, like a snake’s or a vampire’s. Scientists think that the first spiders to evolve were similar to mygalomorphs.
a chemical used to pass signals between nerve cells.
N-terminal domains
the end of an amino acid/peptide/protein with a nitrogen (+3 hydrogens). On the other end, there is the C-terminus: a carbon (+2 oxygens). Kind of like the studs and sockets on LEGO, amino acids attach to each other by the N-terminus of one molecule bonding to the C-terminus of another.
the non-walking appendages that flank an arachnid’s mouthparts. In spiders, they are like legs but much shorter, and in males, modified to transfer sperm during mating. In scorpions and pseudoscorpions, they’re pincers. In amblypygids and vinegaroons, they’re grabby claws. And so on.
the “building blocks” of proteins. Peptides themselves are made built out of a type of molecule called amino acids. A peptide is made up of a few amino acids stuck together in a row, and a protein is made of a lot of peptides stuck together in a row.
the evolutionary history or “family tree” of related species (or higher categories), reconstructed from genetic data and physical traits.
if you eat/bite/lick this thing, you can ingest a toxic substance and get sick. Unlike a venomous animal, if a poisonous animal bites you, it won’t necessarily make you sick.
a behaviour where ticks sit on the tips of leaves or grasses and wave their front legs, waiting for a host to latch on to.
the spikes or hairs on spiders’ legs. They often have the ability to sense things, like vibration or smells. The singular form is seta.
a package of sperm; for example, in the pseudoscorpion Lustrochernes, it looks like a little glass flower on a delicate stalk.
spider silk protein. The word comes from spider + -in, which is a common protein name ending—think “hemoglobin” or, well, “protein”. It is liquid inside a spider’s body, and turns into tough fibers as it is expressed by the spinnerets.
taxonomic bias
a situation where scientists are more likely to publish studies about certain groups of animals over others. This may be because researchers think certain animals are more important than others, and/or it is easier to get funding to study certain animals.
transcription factor
a type of protein that gloms onto DNA and affects how often genes are expressed. Because there are so many different kinds of transcription factors, their effects can be varied: some turn genes on and off, others only do so in specific parts of the body or at specific times in development. Changes in how genes are expressed, as done by transcription factors and other systems, are a big reason that we can share most of our DNA with other animals and yet look so different. For an audio/visual example, see A Capella Science.
long hairs that arachnids use as sensory organs.
if this animal bites you, it can inject a toxic substance and make you get sick. Unlike a poisonous animal, if you eat/bite/lick a venomous animal, it won’t necessarily make you sick.
the “belly” side. In animals like insects and spiders, it’s their bottom side.