A recent study suggests that insects branched out from crustaceans
95 comments
·April 11, 2025Imnimo
I'm so used to seeing the "fish crawling onto the shore" cartoon of evolution that I assumed the branching always went that way - land creatures are branchoffs of sea creatures. But surely this is oversimplified - are there examples in the other direction, where a branching occured in land animals and one branch then returned to the sea?
showerst
I think all marine mammals fit this, right?
Calavar
Yes. And for a non animal example, there's sea grass, which evolved from land grasses.
SideburnsOfDoom
And for an animal but non-mammal example, there are penguins.
nonameiguess
Mangroves are aquatic trees that evolved from regular land trees.
nyanpasu64
Sea grass is a monocot but belongs to a different order (Alismatales) than true grass (Poales).
chasil
ajross
Also ichthyosaurs' ancestors were terrestrial reptiles, though the whole branch is now extinct.
maxbond
Not an animal, but many marine algae descend from freshwater algae, possibly because the last Snowball Earth event may have wiped out the marine algae by covering the oceans with ice (while freshwater algae survived in structures like cryoconites, tiny freshwater puddles that form on glaciers).
https://www.youtube.com/watch?v=D0R3FVTLvT0
(People who know their taxonomy will notice that I'm conflating algae and cyanobacteria, mea culpa.)
nn3
There are also lots of extinct examples like Ichthyosaurs, Mosasaurs, Plesiosaurs
Modern examples are saltwater crocodiles, sea turtles or sea snakes
nyanpasu64
> Hyraxes have highly charged myoglobin, which has been inferred to reflect an aquatic ancestry.[20]
lmpdev
Interesting thing about the evolution of Hyraxes is that it is likely to be an example of a Hard Polytomy - as in Hyraxes, Elephants and Manatees split off simultaneously
SideburnsOfDoom
I knew that Hyraxes were related to elephants, And I've seen rock hyraxes in the wild many times, but TIL the term "Hard Polytomy" https://en.wikipedia.org/wiki/Polytomy
yndoendo
Hippos come from the whale branch. https://en.m.wikipedia.org/wiki/Whippomorpha
elevaet
Hippos don't come from the whale branch, but they share a branch with whales. From wikipedia:
> It is unknown whether the last common ancestor of whales and hippos led an aquatic, semiaquatic/amphibious, or terrestrial lifestyle
However, whales are a great example of a clade that went land -> water in their evolutionary history.
Qem
Sloths (formely): https://en.wikipedia.org/wiki/Thalassocnus
dcminter
Whales are the first example that springs to mind.
abeindoria
I strongly suggest reading Neil Shubin's "Your Inner Fish" which explains a bit more on how different bits etc evolved if you're interested in the topic.
dboreham
Makes sense: a coastal cave is a great environment where an organism can experiment with moving from water to land.
This article also nicely highlights how some scientists can just make stuff up, subsequently overturned when someone finds a fact-based way to evaluate their erroneous conclusions. See also archeology.
nmstoker
For a fairly science focused article I was a little surprised they referred to "bugs" in the casual / technically incorrect manner, as covered here:
https://en.m.wikipedia.org/wiki/Insect#Distinguishing_featur...
nescioquid
As a lay-person who likes to read about bugs, I've come to expect the qualifier "true" to connote something special about bug's "mouth parts".
dhosek
“Bats: Bug Scourge of the Skies!“
willis936
I suspect crustacean allergies are actually arthropod allergies. I haven't seen much research on this though.
xipho
I suspect arthropods are way too diverse to fall under a single umbrella of "is_allergic". Millions of years of evolution can produce very radically different things for our bodies to worry about. Just the fact that there are no marine insects (completing their lifecycle within an ocean) tells us something about how different their biologies, and therefor allergenic "surface" are. Poison pathways from venom can target completely different systems in a humans.
andrewflnr
Almost no marine insects. https://en.wikipedia.org/wiki/Halobates
Re lifecycle:
> The coastal species lay their eggs close to the water surface on rocks, plants, and other structures near the shore, while the oceanic species attach their egg masses on floating objects such as cuttlebone and feathers.
xipho
I know of Halobates, they live on top the ocean, not in the ocean. I.e. they have no adaptations to breathe in salt water. There are many other species like this that are restricted to tidal (flies, parasitic wasps, etc.) or costal areas and nowhere else, but again, not under water.
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willis936
Okay but they both have exoskeletons that have many shared proteins. Allergies are just a protein check.
echelon
It's an allergic reaction to tropomyosin, which is found in shellfish and cockroaches.
I recall an anecdote of an entomologist who studied cockroaches in particular claiming to have developed a shellfish allergy from her work.
saghm
If this were a sci-fi movie, it would be because the cockroaches were sentient and trying to protect themselves.
senkora
People with shellfish allergies are generally advised to avoid eating crickets for this reason.
ljsprague
There is a tree-dwelling shrimp.
https://www.metafilter.com/201489/A-shrimp-that-dwells-in-tr...
SideburnsOfDoom
There seem to be a lot of semi-terrestrial shrimp. The article mentions "beach-hoppers" or "sandhoppers", which are this long list: https://en.wikipedia.org/wiki/Talitridae
AIPedant
Woodlice - e.g pillbugs / roly-polies - aren't shrimp, but they are crustaceans, probably evolving from something like a trilobite.
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anigbrowl
I'm surprised to learn anyone thought otherwise.
pfdietz
The previous theory, it seems to me, is that crustaceans and insects were separate -- that is, they shared a common ancestor, but each is a clade. The new idea is that insects are slotted inside the larger tree of crustaceans, and are more related to some crustaceans than to others.
upghost
whoa whoa whoa I was told everything evolves into crabs[1]:
fallat
This seems so obvious
CommenterPerson
Biology was always a mystery in college, but I have also felt that this was obvious. They look very similar for heaven's sake! My paranoid self thinks shrimp, crabs and lobsters are labeled differently from bugs, so people can eat them without being repulsed.
andrewflnr
Compared to the alternative that, IIRC, insects are closer to myriapods? Crustaceans aren't the only crunchy animals, even after this reorganization.
The title should mention the 2023 year, as reference for "recent".
As explained in the article, this is actually old news.
There has been more than a decade since it is well known that the hexapods a.k.a. insects have evolved from within a certain group of crustaceans, which includes the water fleas.
The 2023 research paper linked in the article has only provided stronger evidence for this.
The main implication of this discovery is that the myriapods (e.g. millipedes and centipedes) are much more remotely related to insects than it has been believed in the past and they have adapted to a terrestrial life completely independently and much earlier than the insects (the invasion of the land by major animal groups has happened in the order myriapods, then arachnids, then hexapods a.k.a. insects, then tetrapod vertebrates, by a coincidence in decreasing order of the number of legs).