Animal field guide
Collector Urchin
Tripneustes gratilla
Pieces of shell, rock, seagrass and seaweed held over its upper surface by its tube feet give this large, short-spined sea urchin a loose cover, thought to shade it from strong sunlight and hide it from predators. It lives on shallow Indo-Pacific reefs and seagrass beds.
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Marine invertebrate · South Asia · Shallow warm seas · Spines grouped in vertical tracts · Relatively common
Known for: Rounded, Dense, Spines often white, Spines grouped in vertical tracts separated by
Animal field guide
Collector Urchin
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Pieces of shell, rock, seagrass and seaweed held over its upper surface by its tube feet give this large, short-spined sea urchin a loose cover, thought to shade it from strong sunlight and hide it from predators. It lives on shallow Indo-Pacific reefs and seagrass beds.
Native range
Natural range, not this capture location
Shallow warm seas: seagrass meadows, algae-covered reef flats, rubble and lagoons, from the low-tide line down to about 30 metres, across the Indian Ocean, Red Sea and western and central Pacific.
Search near meAnimalDex stats
Dominance
10
Speed
2
Size
8
Intelligence
3
Rarity
32%
Total
55
Size scale
STEP 2 · PROVE IT
STEP 3 · BATTLE & FUSE
Understand the animal
Understand the Collector Urchin
Factual biology first: what this animal is like, where it lives, how it survives, and why those traits exist.
01
Introduction to Collector Urchin
Pieces of shell, rock, seagrass and seaweed held over its upper surface by its tube feet give this large, short-spined sea urchin a loose cover, thought to shade it from strong sunlight and hide it from predators. It lives on shallow Indo-Pacific reefs and seagrass beds.
How to identify a Collector Urchin
- Rounded, slightly flattened test up to about 10 to 15 centimetres across
- Dense, short spines, mostly around a centimetre long
- Spines often white, orange or reddish against a darker test
- Spines grouped in vertical tracts separated by narrow, sparsely spined lanes
Why Collector Urchin are interesting
- Hatchery-raised collector urchins have been released in Hawaii to graze down invasive seaweed on reefs.
- Its roe is eaten in several countries, and it is harvested and farmed in parts of the Philippines.
- Populations can boom and crash, and mass grazing can strip seagrass beds bare.
- In aquaculture it has been reported to reach breeding size within about a year.
02
Adaptations and biological abilities
03
Why does Collector Urchin behave this way?
- Rounded, slightly flattened test up to about 10 to 15 centimetres across
- Dense, short spines, mostly around a centimetre long
- Spines often white, orange or reddish against a darker test
- Spines grouped in vertical tracts separated by narrow, sparsely spined lanes
It has no brain and no sleep in the usual sense. It grazes both by day and by night, and in some places moves more in darkness.
04
Why Shallow warm seas?
Habitat: Shallow warm seas: seagrass meadows, algae-covered reef flats, rubble and lagoons, from the low-tide line down to about 30 metres, across the Indian Ocean, Red Sea and western and central Pacific.
Native range: South Asia, Southeast Asia, East Asia, Australia & Oceania, Indian Ocean, North Pacific, South Pacific, Coral Triangle, Red Sea, Southeast Asia Coastal, Australia Coastal
Native range
Natural range, not this specific capture location.
Some regional overlays are unavailable in this web build.
Shallow warm seas: seagrass meadows, algae-covered reef flats, rubble and lagoons, from the low-tide line down to about 30 metres, across the Indian Ocean, Red Sea and western and central Pacific.
05
Why this diet?
Grazes seaweed and seagrass, scraping and biting with the five-toothed jaw apparatus called Aristotle's lantern. It can eat large amounts of algae and moves slowly across the bottom as it feeds.
06
Activity, rest, and lifespan
It has no brain and no sleep in the usual sense. It grazes both by day and by night, and in some places moves more in darkness.
A fast-growing, short-lived urchin, thought to live only a few years, perhaps three to five.
07
Collector Urchin reproduction
Sexes are separate. Females release millions of eggs into the water, where they are fertilised; the free-swimming larvae feed on plankton for several weeks before settling and changing into tiny urchins. There is no parental care.
Males and females look the same; sex can only be told when they spawn or by examining the gonads.
08
Predators, threats, and defense
Triggerfish, pufferfish, wrasses and some large snails eat it. Its short spines and habit of sheltering in rubble and seagrass help protect it.
09
Conservation and rarity
Rarity: Relatively common · 32/100. AnimalDex canonical rarity score: 32/100, maintained by the live indexed species profile.
- Observe from a respectful distance and avoid changing the animal's behavior.
- Do not block feeding, shelter, nesting, or travel routes.
- Use a live camera capture without handling or staging wildlife.
Speak to the animal
Speak to the Collector Urchin
It answers as itself: ask about how it lives, or bring it something of yours and hear what it would do, from its own Power.
Anonymous: 3/day. Signed-in: 10/day. Pro: 100/day.
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Where to find them
Where to find Collector Urchin
To find Collector Urchin in the wild, focus on the exact habitat patches that match its body design and daily behavior, not just the broad country where it exists. You usually do better by working one good piece of habitat inside south Asia, Southeast Asia, East Asia, Australia & Oceania, Indian Ocean, North Pacific, South Pacific, Coral Triangle, Red Sea, Southeast Asia Coastal, Australia Coastal than by covering too much ground.
- Quiet marsh edges, reedbeds, river bends, or shallow wetland margins
- Open grassland edges, lightly wooded plains, or raised ground where you can scan long distances
- Headlands, reef edges, island colonies, tidal channels, or productive coastal water
Scientific name
Tripneustes gratilla
Category
Marine invertebrate
Habitat
Shallow warm seas: seagrass meadows, algae-covered reef flats, rubble and lagoons, from the low-tide line down to about 30 metres, across the Indian Ocean, Red Sea and western and central Pacific.
Rarity
Relatively common · 32/100
Native range
South Asia, Southeast Asia, East Asia, Australia & Oceania, Indian Ocean, North Pacific, South Pacific, Coral Triangle, Red Sea, Southeast Asia Coastal, Australia Coastal
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