TankBud

Mediterranean purple urchin

Paracentrotus lividus

Also known as Rock urchin, Stony sea urchin, Mediterranean purple sea urchin, Rock sea urchin

SaltwaterInvertebrate

Mediterranean purple urchin (Paracentrotus lividus)
Diego Delso · CC BY-SA 4.0

Care at a glance

Temperature
54–75°F
12–24°C
pH
8.1–8.4
Adult size
2.8 in
7 cm
Minimum tank
40 gal
150 L
Temperament
Peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Bottom
Diet
Herbivore
Difficulty
Difficult
Breeding
Hard
Rarity
Very rare
Reef safe
Not reef safe
Family
Parechinidae
Origin
Mediterranean and north-east Atlantic rocky shores, Ireland to Morocco and the Canaries

Overview

The Mediterranean purple urchin is a peaceful grazer for a cool marine tank, not a reef tank. It is for experienced keepers.

Did you know

Along wave-beaten shores, the Mediterranean purple urchin lives in pits it has bored into limestone and sandstone with its own teeth. Some are so deep that the urchin can never leave. Old rock faces in Brittany and Ireland are pocked with rows of urchin-sized holes made this way.

Caring for the Mediterranean purple urchin

Keep the Mediterranean purple urchin in a temperate setup with other Mediterranean or north-east Atlantic animals. Give it at least 40 gal (150 L), with rock and strong flow. It needs cool water, so a home tank usually takes a chiller.

Hold the water at 54 to 75°F (12 to 24°C) and a pH of 8.1 to 8.4. Keep the oxygen high and the salinity at full marine strength, since it does not tolerate low salinity. Drip acclimate it, and never use copper.

It is undemanding about food, so feed kelp, dried seaweed and algae wafers. In any tank it will eat every macroalga and seagrass and scrape the coralline off the rock. Breeding it is hard.

Good to know

Paracentrotus lividus is a regular urchin in the family Parechinidae. Its test is flattened, with spines that are usually purple but can be brown, olive or green. It is the edible urchin of Mediterranean cooking, harvested for its roe from Ireland to Greece and raised in hatcheries. Some fished populations have collapsed. It is not collected for the US aquarium trade, so you will only meet it in European temperate tanks or as seafood. Heat kills it, and field and lab work in the eastern Mediterranean found mass mortality once water passed about 30°C.

In the wild

The Mediterranean purple urchin lives on rock, in boulder fields, tide pools and seagrass meadows, mostly at 0 to 20 m. Its range covers the Mediterranean and the north-east Atlantic, from western Scotland and Ireland to Morocco, the Azores and the Canary Islands. It eats red, green and brown algae and seagrass, and it is one of the main grazers of Mediterranean shallows. It is a temperate animal. Where it is common, winter water runs 10 to 15°C and Mediterranean summers reach the mid 20s.

Common questions

What size tank does a Mediterranean purple urchin need?

A Mediterranean purple urchin needs at least 40 gal (150 L). It spends most of its time in the bottom.

What temperature and pH does a Mediterranean purple urchin need?

A Mediterranean purple urchin is comfortable at 54–75°F (12–24°C) with a pH of 8.1–8.4.

What does a Mediterranean purple urchin eat?

A Mediterranean purple urchin eats kelp, dried seaweed and algae wafers. It will also eat every macroalga and seagrass in the tank and scrape the coralline off the rock.

How big does a Mediterranean purple urchin get?

An adult Mediterranean purple urchin reaches about 2.8 in (7 cm).

Related species