Beautiful coloured Starfish | ©Lynne Tuller  (Mombasa, Kenya)

This starfish is Pentaceraster mammillatus, a species in the family Oreasteridae (order valvatida), characterized by having interadial spines green with orange tubercles [1].

Sometimes this sea star is called Common Knobbed Starfish. The specific name mammillatus refers to the rows of nipple-like protuberances that cover the surface of the animal and give it a studded or armored appearance.

The known distribution of this starfish covers the Indian Ocean and the Red Sea. In 2008 was documented its presence in Singapore waters [2].


Knobbly Sea Star (Protoreaster nodosus)
Hausmann Marketing & Aquarium, 4th January 2009

The life of a juvenile Knobbly Sea Star - worth just $4.50.

And there I was thinking that every encounter with this rare gem on our shores was priceless.

Horned sea star / コブヒトデ

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Protoreaster nodosus

Horned sea star cuddling each other on good terms. 仲良く寄り添うコブヒトデ

Animalia Echinodermata Asteroidea Valvatida Oreasteridae
動物界 棘皮動物門 ヒトデ綱 アカヒトデ目 コブヒトデ科

The photo taken at Kamogawa Seaworld, Chiba, Japan.

Protoreaster nodosus

Common names: Knobbly Sea Star, Chocolate Chip Sea Star, Horned Sea Star, Rhinocerous Sea Star.

Protoreaster nodosus (Valvatida - Oreasteridae) is a species of sea star with broad geographic distribution in the western tropical Pacific and Indian Ocean, ranging from the Seychelles to Australia and Japan to southernmost China. It can be found in depths from 1 to 30 m.

The Knobbly sea stars are very variable in color, they can be brown, green, orange, and even blue. Normally these sea stars have five arms, but can be found specimens with six arms. The body is robust and the dorsal surface (aboral) presents tubers or nodules arranged radially to the arms, starting from a central circle. Adults can reach diameters up to 40 cm.

References: [1] - [2]

Photo credit: ©James Koh [wj]

Locality: Singapore

Mosaic Cushion Star - Halityle regularis

The Mosaic Cushion Star, Halityle regularis (Valvatida - Oreasteridae), is a species of sea star distributed in the Indo-West Pacific, characterized by having a pentagonal body with regular triangular papular areas arranged in hexagons, and the arms completely reduced in size. 

Sea stars are frequently inhabited by symbiotic animals of various taxonomic groups, ranging from protists to fish. Halityle regularis has symbiotic relationships with the Starfish Shrimp, Periclimenes soror, and with the polychaete Hololepidella millari.

References: [1] - [2] - [3]

Photo credit: ©Bernard Dupont (CC BY-NC-SA 2.0) | Locality: Tanjung Kubur, Lembeh Strait, Sulawesi, Indonesia (2009)

Culcita schmideliana | ©Benjamin Naden  (Lembeh, Indonesia)

Although all sea stars are beautiful, Culcita schmideliana is one of the breathtaking species due to the intense color of some specimens (as shown in the picture).

Commonly named Spiny cushion star or simply Cushion Star, Culcita schmideliana (Oreasteridae) is a pentagonal sea star, that has a variety of colors in different patches. It doesn’t have arms and lives in tropical waters [1] of the Indo Pacific.

Typically this pin-cushion star has dark grey background with small irregular pink patches mostly adjacent to black tubercles [2]. However there is great variation to the pattern.

Pin Cushion Seastar (red) | ©Marta Rubio Texeira                            (Negros Oriental, Philippines)

Culcita novaeguineae is a starfish characterized by its cushion shape and short arms that morph very gradually into the central disc. It is a bottom dweller on sandy substrates, feeding on sessile prey. It is found in coral reefs all over the Indo-Pacific [source].

Animalia - Echinodermata - Asteroidea - Valvatida - Oreasteridae - Culcita - C. novaeguineae

Biscuit sea star

Due to its shape and color, this thick, neatly shaped sea star, scientifically named Goniodiscaster scaber (Valvatida - Oreasteridae), is commonly referred to as Biscuit sea star.

These sea stars have almost always five arms, rather short with rounded tips and smooth sides (no spines) so that the sea star looks like it was cut out with a cookie-cutter. The upper side has a neat texture of rounded bumps, and generally is shades of brown, with regular, neat patterns of spots and bars in darker brown, yellow, orange or white. Patterns may vary among individuals. 

The species occurs in the Western Central Pacific.

References: [1] - [2]

Photo credit: ©[wj]

Locality: unknown

Protoreaster nodosus / コブヒトデ

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Protoreaster nodosus

コブヒトデ Horned sea star

Animalia Echinodermata Asteroidea Valvatida Oreasteridae
動物界 棘皮動物門 ヒトデ綱 アカヒトデ目 コブヒトデ科

Sunshine Aquarium, Tokyo, Japan.

Choriaster granulatus / カワテブクロ

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Choriaster granulatus

皮手袋 Granulated sea star

Animalia Echinodermata Asteroidea Valvatida Oreasteridae
動物界 棘皮動物門 ヒトデ綱 アカヒトデ目 コブヒトデ科

Numazu Deepbule Aquarium, Shizuoka, Japan.

Cushion star / マンジュウヒトデ

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Culcita novaeguineae

片手サイズのマンジュウヒトデ。かわいい。 The hand-sized Cushion star. Cute.

Animalia Echinodermata Asteroidea Valvatida Oreasteridae
動物界 棘皮動物門 ヒトデ綱 アカヒトデ目 コブヒトデ科

Kushimoto Marine Park, Wakayama, Japan.

Pentaceraster alveolatus / コブヒトデモドキ

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Pentaceraster alveolatus

Pentaceraster alveolatus コブヒトデモドキ

Animalia Echinodermata Asteroidea Valvatida Oreasteridae
動物界 棘皮動物門 ヒトデ綱 アカヒトデ目 コブヒトデ科

Okinawa Churaumi Aquarium, Okinawa, Japan.