# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/Da-u1jbAGVf
- **Gondola URL:** https://gondola.cc/posts/68267170-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/9940617bc0.jpg
- **Posted:** 2026-07-19T15:54:21.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

A cuttlefish is almost certainly colourblind, and still out-camouflages every animal in the sea.

The skin is the trick. Sepia officinalis carries up to around 200 chromatophores per square millimetre, each an elastic sac of pigment ringed by radial muscles wired directly to the brain. No hormones, no waiting. The muscles pull, the sac flattens into a disc, and the colour appears in tens of milliseconds. Relax, and it snaps shut by elastic recoil. A display panel driven like a muscle.

Underneath sit two more layers doing the optical heavy lifting:

- Iridophores, stacks of reflectin protein platelets acting as tunable Bragg reflectors, producing structural blues and greens no pigment in the animal can make
- Leucophores, broadband scatterers that bounce back whatever ambient light is present, so the animal matches local illumination without measuring it

The eye is the strange part. One visual pigment means one channel, which should mean no colour vision. But the pupil is a W, the lens is graded, and the optics are deliberately blurry in a chromatic sense. One leading idea is that cuttlefish sweep focus and read colour from which wavelength lands sharpest. They also see polarised light, a channel that cuts straight through the glare of open water.

Inside there is a cuttlebone: chambered aragonite, over 90 percent void, with the gas to liquid ratio adjusted osmotically to hold neutral buoyancy. It is why they hover rather than swim. Their blood runs blue-green on copper-based haemocyanin, pushed by three hearts, two feeding the gills and one the body.

Season is set by biology rather than convenience. In the Channel, cuttlefish mass inshore in spring to spawn in shallow water, which is when the pot and trap fishery works. Offshore trawling takes them later in the year. They spawn once and die, all of that neural machinery running on a lifespan of roughly one to two years.

Brilliance, spent in a single season.

#stemantics #marinebiology #cephalopods #cuttlefish #biomimicry

## Stats

- **Views:** 12,351
- **Likes:** 290
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## Tags

cephalopods, cuttlefish, marinebiology, stemantics, biomimicry

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