41 photos - 17 species
Introduction
The spines of the sea urchins sit on small humps
and are partially movable by muscles.
The formation of the spines, their size,
function etc. can vary greatly depending on the species.
There are three main types of regular sea urchins
and ten to twelve types of irregular sea urchins.
The spines are mainly used as protection against predators such as starfish,
large snails and fish and in some species can even release poison when they bite, leather sea urchins (fire sea urchins) are particularly poisonous.
There are sea urchins that drill their spines into hard substrates
such as coral reefs and rocks.
In rare cases, food propelled by the spines is captured.
Inhabitants of sandy bottoms also use their spines for locomotion.
If you step on a spine, it may break off and get stuck in your foot,
which can lead to painful purulent inflammation.
In some species, the spines are also difficult to remove.
Asthenosoma marisrubri
Red sea fire urchin
Maximum diameter with spines: 25 cm
This very beautiful sea urchin is extremely poisonous.
Active at night, white poison blisters at the tips of the spines,
their stings are very painful.
Photo 1 Johnny: Hurghada Egypt
Photos 2 - 3 Johnny: Lembeh Strait North - Sulawesi
Asthenosoma varium
Fire urchin or Variable fire urchin
Maximum size: 25 cm
Very beautiful sea urchins, but also very poisonous.
I can tell you a thing or two about it,
unfortunately I wasn't paying enough attention
when photographing one of these sea urchins
and touched one with my hand that was slightly in front of the one,
I was photographing. It was the most painful experience I've had underwater,
fire corals are nothing compared to that.
So be careful!!!
They have a variable colouring.
Photo 1 Astrid: Bangka Island North Sulawesi
Astropyga radiata
Blue-spotted sea urchin, Red sea urchin or Radiant sea urchin
Maximum size: 45 cm
Dark red spines standing in groups,
radial zones with rows of bright blue dots that are free of spines.
They are found on sandy soils, often in groups (photo 3).
The spines can cause painful injuries.
Photo 1 Astrid: Lembeh Strait North - Sulawesi
Photos 2 - 3 Johnny: Lembeh Strait North - Sulawesi
Photos 4 - 5 Johnny: Bangka island North - Sulawesi
Diadema antillarum
Long-spined sea urchin
Maximum size: 20 cm
Depth: 0 - 40 m
Common in Caribbean waters, it is a harmless algae eater, but divers,
snorkellers and bathers should be very careful with this animal.
Its fine prickly spines easily penetrate the skin and break off,
causing infections and painful wounds!
The spines of the sea urchin are dark purple to black, sometimes greyish to white.
The spines of young sea urchins can be banded.
Photo 1 Astrid: Bonaire Caribbean
Photo 2 Johnny: Hurghada Egypt
Photo 3 Johnny: Bonaire Caribbean
Diadema paucispinum
Diadema paucispinum
Maximum diameter: 25 cm
Thanks to their spines, they are well protected from predators
and also offer many animals such as small fish or fry very good protection from predators.
Active at night, perfectly wedged into reef holes during the day.
Photo 1 Johnny: Bangka Island North Sulawesi
Diadema setosum
Diadema urchin, Black longspine urchin or Porcupine sea urchin
Maximum diameter with spines: 50 cm
It causes painful wounds with its long poisonous spines.
It has 5 light sensory organs that can be recognised as white dots.
Often in dense groups.
Scrapes off algae.
Photo 1 Johnny: El Qesir Egypt
Photos 2 - 3 Johnny: Hurghada Egypt
Echinometra viridis
Reef urchin
Size: 8 - 12 cm
Depth: 0 - 40 m
Found under rubble, in rocky areas and coral reefs, as well as in crevices.
Reddish-brown body with medium-length greenish spines,
a paler base and dark, often purple tips.
Photo 1 Astrid: Bonaire Caribbean
Echinothrix calamaris
Banded sea urchin or Double spined urchin
Maximum diameter with spines: 30 cm
The spines are cross-banded and poisonous.
Inhabits shallow rock and coral reefs.
Photos 1 - 3 Johnny: Hurghada Egypt
Eucidaris tribuloides
Slate pencil urchin
Maximum diameter with spines: 10 cm
Depth 3 - 23 m
Thick, cylindrical and blunt spines.
Light to dark reddish-brown body.
Their spines are often covered with various organisms.
Often hidden in sheltered places.
Photo 1 Astrid: Bonaire Caribbean
Heterocentrotus mamillatus
Slate pencil urchin
Maximum diameter with spines: 30 cm
This species is wedged in reef crevices during the day and eats algae at night.
Photos 1 - 5 Johnny: Hurghada Egypt
Photos 6 - 7 Johnny: Moalboal Philippines
Lytechinus williamsi
Jewel urchin
Maximum size: 5 - 8 cm
Maximum depth: 3 - 25 m
Round body, densely overgrown with short spines that fade from green to white.
Fine red lines and purple-coloured pods are clearly visible between the spines.
Food: algae
Photo 1 Astrid: Bonaire Caribbean
Mespilia globulus
Tuxedo urchin, Sphere urchin or Globe urchin
Maximum size: 6 cm
5 or 10 spiny bands, with a blue field without spines in between.
At home on rubble and hard ground, where it scrapes off algae.
Photo 1 Johnny: Bangka Island North - Sulawesi
Photo 2 Astrid: Moalboal Philippines
Metalia sternalis
Sea urchin
Maximum length: 5 cm
Maximum depth: 5 - 25 m
The fine spines/hairs that the heart sea urchin has all over its body are striking,
presumably for its protection.
Like all heart urchins, it lives buried in the sand.
Photos 1 - 2 Johnny: Bangka Island North - Sulawesi
Microcyphus rousseaui
Bald-patch urchin
Maximum diameter with spines: 5 cm
It has 5 zigzag lines around its body, they have no spines at these points.
Lives among seaweed, rubble and rocks.
Rarely found.
Photos 1 - 2 Johnny: Hurghada Egypt
Parasalenia gratiosa
Red urchin
Maximum diameter with spines: 5 cm
This hedgehog is usually found in water depths of up to 70 metres.
Photo 1 Johnny: El Qesir Egypt
Photos 2 - 3 Johnny: Bali Indonesia
Tripneustes gratilla
Pincushion hairy urchin, Cake sea urchin or Sea lamington
Maximum size: 12 cm
Depth: up to 25 m
Venomous, pincer-like appendages.
Variable colours: from cream to red or black.
Often camouflages itself with waste material.
Photos 1 - 2 Johnny: Hurghada Egypt
Tripneustes ventricosus
West indian sea egg
Maximum diameter with spines: 15 cm
Depth: 0 - 10 m
Densely covered with short, white spines.
The body is mostly black, but there are also dark purple or reddish-brown ones.
Found in seagrass beds, sometimes also in shallow reefs.
Photo 1 Johnny: Bonaire Caribbean