The family Diadematidae has around 30 extant species, including some of the most common tropical sea urchins species (Diadema antillarum, Diadema setosum, Astropyga radiata...).
These are big regular sea urchins, with hollow and usually very long spines, some of them being venomous (but not dangerous for humains). Some are bright colored (especially red or blue), but others are dark, sometimes with ornamental patterns called iridophores (especially Astropyga and Diadema).
One of their most obvious characteristic is to have an "anal papilla" (or "anal cone") on the top of the test : it can be very obvious in some species (Echinothrix calamaris, Diadema setosum) or nearly hidden (Echinothrix diadema, Centrostephanus longispinus).
The most common genera found at diving depths are Diadema, Echinothrix, Astropyga and Centrostephanus ; other genera like Chaetodiadema are found only in deep waters.
Most of them inhabit tropical waters of the indo-pacific.
Among their skelettal characteristics, they have trigeminate ambulacra, with perforated tubercles, almost always crenulate.
The Diadematidae are a family of sea urchins. Their tests are either rigid or flexible and their spines are long and hollow.[2]
Like other sea urchins diadematids are sensitive to touch, light, and chemicals; additionally they do have eyes (eye spots) which is in contrast to other sea urchins. Because of this they can follow a threat with their spines.[4]
Media related to Diadematidae at Wikimedia Commons
The Diadematidae are a family of sea urchins. Their tests are either rigid or flexible and their spines are long and hollow.
Astropyga Gray, 1825 Astropyga radiata (Leske, 1778), extant Astropyga pulvinata (Lamarck, 1816), extant Astropyga magnifica (Clark, 1934), extant Centrostephanus Peters, 1855 Centrostephanus asteriscus (Agassiz & Clark, 1907), extant Centrostephanus coronatus (Verrill, 1867), extant Centrostephanus fragile (Wiltshire in Wright, 1882), Santonian, Maastrichtian, Danian Centrostephanus longispinus (Philippi, 1845), extant Centrostephanus nitidus (Koehler, 1927), extant Centrostephanus rodgersii (Agassiz, 1863), extant Chaetodiadema Mortensen, 1903 Chaetodiadema granulatum (Mortensen, 1903), extant Chaetodiadema keiense (Mortensen, 1903), extant Chaetodiadema tuberculatum (Clark, 1909), extant Diadema Gray, 1825 Diadema palmeri (Baker, 1967), extant Diadema savignyi (Audouin, 1829), extant Diadema setosum (Leske, 1778), extant Diadema antillarum (Philippi, 1845), extant Diadema paucispinum (Agassiz, 1863), extant Diadema mexicanum (Agassiz, 1863), extant Diadema ascensionis (Mortensen, 1909), extant Echinodiadema Verrill, 1867 Echinodiadema coronata (Verrill, 1867), extant Echinothrix Peters, 1853 Echinothrix calamaris (Pallas, 1774), extant Echinothrix diadema (Linnaeus, 1758), extant Eodiadema, Lower Jurassic Eremopyga Agassiz & Clark, 1908 Eremopyga denudata (De Meijere, 1904), extant Goniodiadema Mortensen, 1939 Goniodiadema mauritiense (Mortensen, 1939), extant Kamptosoma Mortensen, 1903, extant Palaeodiadema (Pomel, 1887), Santonian, Maastrichtian, Danian Pedinothuria Louis, 1897 Pedinothuria cidaroides (Gregory, 1897), Callovian, Oxfordian
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