Unveiling the 9 Types of Sea Urchins: Spines and Splendor

Sea urchins are captivating spiny creatures residing in the oceans. There are about 950 different types of sea urchins, each boasting a unique appearance. From vibrant shallows to hidden abysses, these intriguing sea urchins will leave you awestruck by the wonders of marine life. Join us on this underwater journey to witness the beauty and diversity of this species.

1. Slate pencil sea urchin

The Slate Pencil Sea Urchin, also known as the Heterocentrotus mammillatus, is one of many types of sea urchins in Hawaii. This striking marine creature is renowned for its unique appearance and habitat. It showcases a striking cylindrical shape, adorned with long, slender, and delicate spines that resemble slender pencils, thus giving it its unique name.

Red slate pencil sea urchin

These spines are red in hue, although variations in brown, yellow, and purple colorations, with a characteristic white ring encircling their base. The red-spine species at night will undergo a surprising transformation, turning into a chalky pink shade.

The Slate Pencil Sea Urchin is commonly found in the warm, tropical waters of the Indo-Pacific region. It favors shallow coral reefs and rocky coastlines, where it can graze on algae and organic debris.

2. Fire urchin

The fire urchin (Astropyga radiata) is also known as false fire urchin, red urchin, or blue-spotted urchin. It is a mesmerizing marine organism inhabiting the shallow waters of tropical reefs and lagoons within the Indo-Pacific region.

The gorgeous fire urchin

Presenting an impressive specimen, the mighty urchin boasts a substantial size, measuring up to 20 cm (8 in) in test diameter. Its long spines, reaching up to 4 cm (1.6 in), form five striking vertical clusters. Fascinatingly, these clusters are interspersed with V-shaped regions, with the absence of spines.

The naked regions exhibit a vibrant crimson hue adorned with mesmerizing azure dots. Meanwhile, the remaining parts of the test and spines display an array of colors, ranging from deep reddish-brown to dark brown, regal purple, or even a velvety black. Their spines are categorized into two types, with the longer spines being hollow whereas the shorter spines being venomous.

3. Pincushion urchin

The Pincushion urchin (Lytechinus variegatus) is also called variegated or green sea urchin. This captivating marine creature is found in the warm waters of the Western Atlantic Ocean. Named for its striking appearance, this echinoderm showcases a spherical body covered in numerous needle-like spines resembling pins on a cushion.

The pincushion sea urchin

It has a size of about approximately 11 centimeters (4.3 in) in diameter. Its vibrant test comes in a delightful array of colors: from regal purple and subdued dull red to captivating white blots or striking green hues. What makes it truly fascinating is the diversity of its spines, which exhibit a unique blend of colors. Picture this: spines that transition from one hue at the base to another shade at the tip, creating a mesmerizing spectacle.

When exploring the Caribbean waters, you’re most likely to encounter the sea urchin sporting either an alluring green test accompanied by equally enchanting green spines or a harmonious pairing of green test with pristine white spines. These delightful combinations are a common sight, adding to the allure of the Caribbean marine life.

4. Banded sea urchin

The Banded Sea Urchin (Echinothrix calamaris), aka double spined urchin, is a fascinating marine creature found in the shallow waters of the Indo-Pacific region. Its distinctive appearance features long, black, and sharply-pointed spines that alternate with creamy-white bands, creating an eye-catching banded pattern along its spherical body.

The banded sea urchin

Nonetheless, this remarkable species exhibits a fascinating variety, showcasing both entirely dark and entirely white morphs. In its deepest hues, it is usually mistaken for the long-spine sea urchin – the most-seen type of sea urchin in the Great Barrier Reef.

5. Sputnik sea urchin

The Sputnik sea urchin, scientifically known as Phyllacanthus imperialis, is a captivating marine creature that has different names, such as lance urchin, imperial sea urchin, land mine sea urchin, or pencil sea urchin.

Named after its striking resemblance to the iconic Soviet satellite, Sputnik, this sea urchin boasts a brown or black spherical body adorned with long, blunt spines. These spines can have different colors. The mesmerizing species live in the Indo-Pacific Ocean.

6. Common sea urchin

The European edible sea urchin (Echinus esculentus) or common sea urchin is a captivating marine creature renowned for its unique appearance. This species boasts a globular-shaped body covered in a spiny exoskeleton, typically adorned with vibrant colors ranging from pink to red to purplish with white tubercles.

Sea urchin adaptions

Its body is adorned with extended, pointed spines, each connected to a small protrusion. Generally, it has a size of 15-16 cm (5.9-6.3 in) in diameter, although exceptional specimens have been documented to reach up to 17.6 cm (6.9 in).

Found abundantly in the cool waters of the northeastern Atlantic Ocean and the North Sea, the European edible sea urchin prefers to inhabit rocky seabeds and kelp forests at depths of 1200 meters. This sea urchin is listed as “Near threatened” by the IUCN.

7. Common heart urchin

The common heart urchin (Echinocardium cordatum) or sea potato is a captivating marine species known for its distinctive appearance and habitat. Presenting a unique echinoderm with an exquisite heart-shaped form, characterized by its flattened, disk-like body enveloped in a captivating dense mat of furrowed yellow spines. These remarkable spines emerge from tiny tubercles and gracefully curve mostly backward.

The heart urchin typically measures around 2 to 3 inches in diameter, making it a relatively small species within the echinoderm family.

Heart urchin - one of weird types of sea urchins

These enchanting creatures are commonly found along sandy and muddy seabeds in the shallow waters of the Pacific Ocean and Atlantic Ocean. Their habitat ranges from intertidal zones to depths of up to 200 meters, where they burrow beneath the sediments, leaving only their spines visible.

8. Burrowing urchin

Meet the elusive spiny ballerina, scientifically known as Echinometra mathaei! This captivating creature is renowned for its sturdy, spherical form adorned with spines resembling elegant, pencil-like twirls. Its alluring color palette often leans towards a rich, dark hue, though the spines might surprise you with their captivating mix of greens and purples, sometimes sporting charming purple tips or an entirely green base with hints of royal purple.

As it gracefully dances through the ocean depths, the burrowing urchin enchants observers with its petite yet notable presence, reaching a modest test diameter of approximately 5 centimeters (2.0 inches).

The burrowing urchin is adapted to life in shallow coastal waters, predominantly found in the Indo-Pacific region.

9. Rock boring urchin

Meet the enigmatic Echinometra lucunter, also known as the rock boring urchin. This fascinating creature boasts an elongated body, adorned with spines of moderate length, characterized by broad bases and razor-sharp tips. Its elegant exterior showcases a captivating range of colors, from deep browns to ebony hues. Intriguingly, the upper side often exhibits a warmer, ruddy tone compared to the lower side. Their spines commonly sport a sleek black shade. The species can attain a remarkable diameter of approximately 8 centimeters (about 3.1 inches).

Rock boring sea urchin - types of sea urchins

As the name suggests, the Rock boring urchin can be found inhabiting rocky substrates and coral reefs along the South American coast and the vast expanse of the Caribbean Sea. Seeking shelter in the shallower waters, this fascinating creature can be spotted anywhere between the intertidal zones and depths of approximately 2 to 45 meters.

9 Types of sea urchins

Those are 9 different species of sea urchins, each exhibiting unique characteristics, adaptations, and ecological roles. From the striking appearance of the purple sea urchin to the elusive and elusive red slate pencil urchin, we have witnessed the extraordinary beauty and complexity of these marine invertebrates.


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We are passionate animal enthusiasts with over a decade of experience studying animals. With a degree in zoology and conservation biology, we've contributed to various research and conservation projects. We're excited to bring you engaging content that highlights the wonders of the animal kingdom. We aim to inspire others to appreciate and protect wildlife through informative content grounded in expertise and passion. Join us as we delve into the captivating world of animals and discover the incredible stories they have to tell.

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