Tergum

A tergum (Latin for "the back"; plural terga, associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the base and posterior edge is called the apex or margin. A given tergum may be divided into hardened plates or sclerites commonly referred to as tergites.[1]

Tergites (with lateral paranota) of a polydesmid millipede

In a thoracic segment, for example, the tergum may be divided into an anterior notum and a posterior scutellum. Lateral extensions of a tergite are known as paranota (Greek for "alongside the back") or carinae (Latin for "keel"), exemplified by the flat-backed millipedes of the order Polydesmida.

Kinorhynchs have tergal and sternal plates too, though seemingly not homologous with those of arthropods.[2]

Tergo-tergal is a stridulatory mechanism in which fine spines of the abdominal tergites are rubbed together to produce sound.[3] This process is known as abdominal telescoping.[3]

Examples
  • Abdominal tergum (divided into several tergites) of a bee.
  • Seven sclerites distinctly visible on the back of a pregnant scorpion.
  • A tergite of this wasp is labeled 19.
  • Thoracic tergites of various trilobites.
gollark: It's easy to say that if you are just vaguely considering that, running it through the relatively unhurried processes of philosophizing™, that sort of thing. But probably less so if it's actually being turned over to emotion and such, because broadly speaking people reaaaallly don't want to die.
gollark: Am I better at resisting peer pressure than other people: well, I'd *like* to think so, but so would probably everyone else ever.
gollark: Anyway, I have, I think, reasonably strong "no genocide" ethics. But I don't know if, in a situation where everyone seemed implicitly/explicitly okay with helping with genocides, and where I feared that I would be punished if I either didn't help in some way or didn't appear supportive of helping, I would actually stick to this, since I don't think I've ever been in an environment with those sorts of pressures.
gollark: Maybe I should try arbitrarily increasing the confusion via recursion.
gollark: If people are randomly assigned (after initial mental development and such) to an environment where they're much more likely to do bad things, and one where they aren't, then it seems unreasonable to call people who are otherwise the same worse from being in the likely-to-do-bad-things environment.I suppose you could argue that how "good" you are is more about the change in probability between environments/the probability of a given real world environment being one which causes you to do bad things. But we can't check those with current technology.

References
  1. McCafferty, W. Patrick (1983). Aquatic entomology: the fishermen's and ecologists' illustrated guide to insects and their relatives. Jones and Bartlett. p. 20. ISBN 9780867200171. Retrieved 2020-04-30 – via Google Books.
  2. Sørensen, MV; Dal Zotto, M; Rho, HS; Herranz, M; Sánchez, N; Pardos, F; Yamasaki, H (2015). "Phylogeny of Kinorhyncha based on morphology and two molecular loci". PLOS ONE. 10 (7): e0133440. Bibcode:2015PLoSO..1033440S. doi:10.1371/journal.pone.0133440. PMC 4511640. PMID 26200115.
  3. Field, Laurence H; Roberts, Kelly L (2003). "Novel use of hair sensilla in acoustic stridulation by New Zealand giant wetas (Orthoptera: Anostostomatidae)". Arthropod Structure & Development. 31 (4): 287–296. doi:10.1016/S1467-8039(03)00005-7.

Further reading
  • Hood, J. Douglas (1958). "The terms tergum and sternum, tergite and sternite". Systematic Zoology. 7 (3): 131–133. doi:10.2307/2411977. JSTOR 2411977.
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