A new animal every day

This was Monday’s animal. Every day has its own page.

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Monday 26 October 2026

An upside-down jellyfish lies on pale sand, its frilly brownish arms facing up inside a round bell with a scalloped rim.
Photo: Paul Asman and Jill Lenoble · CC BY 4.0 · iNaturalist

Picked by voters

Upside-down jellyfish

It was the first animal without a brain found to sleep. After a sleepless night, it’s less active the next day.

Lives in
MangrovesShallow mangroves, mudflats and seagrass beds in tropical and subtropical seas worldwide
More about the upside-down jellyfishScientific name, size and Red List status
Scientific name
Cassiopea
Size
Bell 12.5 cm across on average, up to about 33 cm
IUCN Red List
No single status

The IUCN Red List assesses each species separately, and this photo can’t be narrowed down to one species. What this means

Fact source: Howard Hughes Medical Institute

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This week

Every animal so far
  1. Mon 26Upside-down jellyfishViewing
  2. Tue 27Boxer crabToday
  3. Wed 28Tomorrow’s animalin 20 h 54 min
  4. Thu 29
  5. Fri 30
  6. Sat 31
  7. Sun 1

Why Animall

People can’t care about animals they have never heard of.

Scientists still discover thousands of new animal species every year, while many others are disappearing because of habitat loss and climate change. Some die out before anyone has described them.

10,000+

new animal species are described every year.

University of Arizona, 2025

86%

of species on Earth, and 91% in the ocean, have not been described yet.

Mora et al., 2011

73%

average drop in monitored wildlife populations between 1970 and 2020.

WWF Living Planet Report, 2024