NudisNear Me

What it does

It asks iNaturalist which nudibranchs have been recorded near you in the last 20 years — within 50 km unless you change it — then sorts them by how often they turn up, so the top of the list is your best bet. Choosing rockpooling drops the species that only live below the tide line; choosing diving keeps everything, because anything findable in a rock pool is findable on a dive too.

Settings, behind the gear, let you pull the search area anywhere from 50 km down to 100 m — the steps get finer as you go smaller, so you can sit on one reef without losing the ability to sweep a coastline. Only Research Grade observations count unless you tick the "Needs ID" option, and there is a second pass you can switch on that adds museum and survey specimens from GBIF.

Crowded coastlines

It works anywhere in the world, which means it has to cope with places far richer than New Zealand. Fifty kilometres around Anilao in the Philippines turns up over 400 species — a catalogue, not a list you read before getting in the water. So when a search returns more than 25 species the app pulls the radius in until it doesn't, stopping at 1 km. It tells you when it has done this, and you can override it in one tap. If even 1 km is crowded, the list pages 25 at a time.

Obscured records

iNaturalist protects threatened and sensitive species by publishing a randomised position rather than the real one, scattered by up to roughly 25 km. Narrow the search and those records disappear, even when the animal is genuinely at your feet. The obscured option in settings runs a second 50 km sweep just for them and lists what it finds at the bottom, marked with a dashed border, because there is no way to tell from the data whether they are near you or twenty kilometres away.

Where the shallow/deep split comes from

Three sources, best first. A hand-checked table in depths.js covers New Zealand species and always wins. Behind it sit GBIF occurrence depths, which classify roughly 1,300 species worldwide. Last comes a guess from the genus. Anything still unresolved is shown under both modes and badged depth unknown rather than guessed at. iNaturalist has no depth field at all, and WoRMS holds no depth attributes for these animals.

The GBIF layer needs a caveat. The people who record a depth on an observation are overwhelmingly divers — shore collectors almost never enter one — so the data leans deep. Asking "is this species mainly shallow?" buries genuine rock-pool animals: Doris wellingtonensis is commonest in the top three metres yet reads as 97% deep in GBIF. So the question asked is "is it recorded shallow at all?". A few shallow records count for a lot; an absence of them counts for little unless there is a pile of deep ones behind it. It errs towards showing you a species, on the grounds that a wasted look under a rock costs less than never being told the animal was at your feet.

Photos

Photographs come from iNaturalist and are shown only where the photographer has applied a Creative Commons licence. Each one is credited, and tapping any photo opens it large.

Finding a usable one takes three goes. A species' headline photo is often all rights reserved, so the app then checks the taxon's photo gallery, and if that is also restricted — or holds a single image, as happens more than you would think — it searches the observations themselves filtered by licence. A blank tile means all three came up empty, which is now rare.

Your location

Your position never leaves your device un-rounded — it is snapped to roughly 100 m before any search is sent, which makes no difference across a 50 km radius. It is not stored, and it never appears in the address bar, so nothing can pick it up from there either.

Visits are counted with Google Analytics, which records which screens get used and sets a cookie; nothing that identifies you, and never your location. A tracker blocker stops it without affecting the app.

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