There are a lot of different species of organisms in the world.
And a lot of them happen to look and behave very similarly to each other. Unfortunately, Hollywood thinks that any person who is sufficiently intelligent is also able to name any animal or plant they come across with its specific (and correct) Latin name, taxonomic history, habitat, diet and favorite color. In reality, unless you happen to be a foremost expert in studying that specific creature, it's unlikely that you could say anything more about it than "Hey, that's a bug!"
This is especially wrong when dealing with bacteria or other microscopic organisms, since even though they may look similar at first glance, they could potentially belong to entirely different DOMAINS. And even microbes that are of the same species can look markedly different under different conditions.
With the advent of certain genetic techniques that allow scientists to specifically pin down what organism it is from analyzing its DNA, this is becoming somewhat more reasonable however, but such techniques also take time and significant computing power.
In the same vein, this also applies when somebody sees a species' scientific name and can tell you the rest of its taxonomy from that information alone. This makes sense if they are familiar with the taxon, but otherwise, since the scientific name only gives genus and species, it sticks out as serious research failure. Nor does knowing Latin tell you much from the pseudo-Latin names used in binomial nomenclature; Mephitis mephitis ("Stench stench") would probably be an animal renowned for its stink, but you wouldn't know that it's the striped skunk and not a polecat or stink beetle.
If this is only done with a single rare species, it can be viewed as just a rare bit of knowledge the person at hand happened to possess. Also, knowing your local flora and fauna often allows you to readily identify a plant or animal down to the subspecies, something that would be next to impossible if you did not know where the said plant or animal were collected. People who do a lot of hiking in a particular area would normally recognize the common species of plants and animals found in that area right away, regardless of any background in botany or biology.
Ultimately what classifies this as a Hollywood Science mistake is the assumption that ANYONE who is smart is able to identify a specific organism with uncanny accuracy by looking at a sample that is far too small or incomplete to normally reach that conclusion.
See also Artistic License – Biology.
Examples:
- In Kaguya-sama: Love Is War, both Kaguya and Fujiwara are able to correctly identify a lacquer tree cockroach from a quick glance. And then Karen ups the ante in the spin-off where she's able to do the same thing from a distance (though unlike the other two, her ability to do so is Played for Laughs).
- The Unicorn Tapestries,
a group of seven tapestries dating from circa 1500, show at least 20 distinct types of flowers with more scientific accuracy than botany textbooks from the same period.
- In the Discworld of A.A. Pessimal, zoologist Johanna Smith-Rhodes can do this — up to a point. For a Rimwards Howondalandian she's got the distinction between antelopes, gazelles and deer wrong in one particular case and has also misidentified spider species, with interesting consequences. But everyone has an off day in her job every so often.
- Col_Rutherford's "revised script" of Indiana Jones and the Kingdom of the Crystal Skull changes Indy's line when he sees the carnivore ants from "Siafu!" to "Paraponera clavata!". According to the author, this is because siafu are from Africa, while the other are South American, where the film takes place. Now, as to why would an archaeologist know how to identify ants to species level, let alone from a distance...
- The end of chapter notes for Prehistoric Park: Returned from Extinction tend to include the genus and species name of each creature rescued, something that is usually rather rare, even in the source material and other Prehistoric Park fanfiction. Some chapters include this simply for the sake of keeping things clear to the readers — the mission to rescue dinosaurs from Jurassic North America explicitly lists Big Al as an Allosaurus fragilus. That example, though, was also because ALL Allosaurus species from that time and location were rescued (for reference, North America has five different species of Allosaurus — A. fragilus, A. lucasi, A. jimmadseni, A. atrox, and A. amplus.
- In Deep Rising, a character swiftly identifies the man-eating worms as to their broad taxonomic group and likely behavior, despite the fact that A) he's only seen the things for a few seconds, B) the taxon in question is known only from fossils, and C) he's a freakin' cruise ship designer, not a scientist! Amusingly, he turns out to be completely wrong about what they are. It's all some sort of mutant octopoid monster, not a pack of killer worms.
- In Honey, I Shrunk the Kids, the tiny kids are running away from a gigantic lawn mower and jump into a hole in the ground. Nick immediately identifies the exact species of worm that made the tunnel (despite the worm not even being present). Possibly justified in that they are in his backyard and since he is a science geek, it's at least remotely possible that he knows what species of worm lives in their area (Nick identifies it as a common earthworm, which would likely be most people's first guess anyway).
- In Like Flint: From microscopic traces, Derek Flint is able to identify the residue of exotic flowers and herbs (styrax, ylang, mimosa, hyacinth, cannabis and Macedonian brawley).
- Jurassic Park: Ellie, a paleobotanist, knows from a cursory glance that a certain plant is an extinct species. In all fairness, the character does have a doctorate in paleobotany, and many high-ranking and distinctive taxonomic groups of plants do have few or no living representatives (for instance, the entire phylum of seed ferns has been extinct since the Eocene at the latest, and the order Ginkgoales is represented by only a single living species, Ginkgo biloba).
- Averted in The Silence of the Lambs, in which identifying the species of an insect pupa found on the bodies of victims is a plot point, and the professional entomologist consulted needs time and equipment to answer the question.
- In Them!, Dr Medford identifies the exact species of a dead giant ant with a glance at the body, despite the fact that size is high on the list of characteristics used to identify ant species.
- Averted in Barbara Hambly's The Armies of Daylight. Rudy can instantly identify a small animal from its bones, but he was highly trained in botany/zoology/magic and the question is: 'rabbit or chicken'.
- Common in Dinoverse. Known dinosaur-nerd Betram probably has a reasonable chance of identifying common animals and plants in his favorite part of the Mesozoic. When it's his teacher's turn, well, Mr. London knew about Betram's adventure and regeared all his classes to be about the age of the dinosaurs, so he and his students aren't jumping into things blind, but it's weird how they quickly and unambigiously identify non-stock dinosaurs like Acrocanthosaurus and Hypsilophodon. And back in the first set of books Janine, who's insightful but not markedly interested in dinosaurs, happens to know about the digestive processes of Ankylosaurus.
- Slightly done in Sherlock Holmes when he correctly identifies the lion's mane jellyfish as the killer of the victim when he sees it at the bottom of a small pool. Very much justified, however, in that this is one species which is very distinctive (it's really, really big), that he'd spent a day reading up on it to confirm a vague memory, and that the victim's last words were "the lion's mane."
- Happens in many Jules Verne novels, where The Professor identifies and describes the characteristics of every plant or animal species the protagonists come across, as a means for Verne to show his work. Back then, however, that was what a lot of people read books for, since there was no other means of learning about them save by actually going to see them. The cake is taken by Conseil, a manservant to Prof. Arronax in 20,000 Leagues Under the Sea. The man is a living classification handbook by virtue of having spent so long in scientific company. Amusingly, while Conseil had a remarkable memory for the taxonic classification of species, he had very little idea what they actually look like. By contrast, talented sailor and harpooner but rather Book Dumb Ned Land knows nothing much about taxonomy but can recognize many species of fish by sight. As Arronax remarks, by their powers combined they are one extremely talented marine biologist (even if Ned insists on classifying them solely by whether or not they're good to eat).
- The Beast, the TV-movie adaptation of Peter Benchley's giant-squid-on-the-rampage novel Beast has the resident scientist instantly identify the squid as Archetuthis dux from a single sucker-claw and a whiff of ammonia. Especially bad because Architeuthis the giant squid doesn't have claws. (The colossal squid Mesonychoteuthis does, though.) And most deep sea squid have a lot of ammonia in their systems.
- Subverted in The Big Bang Theory where Sheldon thinks he can identify the specific species of a cricket by its chirping. He is in fact wrong, as pointed out by Howard (who spent his youth collecting insects), though Sheldon refuses to believe it. In the end they turn to an associate with a PhD in entomology to settle the dispute... who identifies the cricket's species with a cursory glance, playing the trope straight. In fact, when asked, Professor Crawley claims he can identify every insect and arachnid in the world. There are 950,000 insect species and 50,000 arachnid species, making this claim rather unlikely. Even more so, arthropods are the single most diverse group on Earth; it is estimated that there are quite literally several million species of insects and arachnids that have not yet been identified, which would make it difficult to ID "any" one finds.
- Bones:
- It once features a character identifying a fungus to species from a few hyphal traces. This is impossible even for trained mycologists.
- And another time, a person whose specialty is in art identifies a specific species of fungal spores thanks to having a boyfriend who studied them. That this is actually accepted in court is a major case of Hollywood Law.
- And then there is Hodgins, for which this trope essentially defines two-thirds of his job. The other third involves doing much the same, only with particulates. He is PhD-qualified for both of these, so it makes more sense than in many of these examples.
- Crossing Jordan had a character (aptly nicknamed "Bug") dedicated to this trope. ANY time there were entomological traces found, ONE look was all he needed to tell what it was and how incredibly few but oh so conveniently dark and abandoned places it could be found.
- CSI proper typically justifies the insect portion of this as Grissom is an entomologist, but has been very guilty of this with regards to the flora.
- In Jagged Alliance 2, everyone has a comment on the monstrous and unearthly creatures you'll inevitably encounter if you tick the "Sci-Fi" option. Most mercenaries express various forms of surprise, but the medical doctors of your team will immediately start pinning down their taxonomy on first sight. (Crustacea, they seem to agree, which amusingly makes them Giant Enemy Crabs.)
- In El Goonish Shive, the principal of Moperville South High School apparently knows the taxonomic family of squirrels. Despite the fact that that is easily recognized by biologists, the fact that he and several others recognize the word "Sciuridae" with presumably little biology experience is notable.
- Professor Lostclock in Hitmen for Destiny is able to name and describe the evolutionary history of more or less every animal in the multiverse.
- Jane Porter from The Legend of Tarzan is able to identify a (typically grossly inaccurate and quite oversized) velociraptor at a glance. Worse still is that fact that she isn't a paleontologist of any sort and in fact the series takes place before velociraptors were scientifically described and named, and many decades before they were recognized in popular public consciousness.
