Why investigate Spondylus?

We are currently investigating the ecology and population dynamics of the bivalve genus Spondylus, also known as “spiny oysters”. The shells are famous for their beauty among collectors worldwide. Visitors of Ecuador have surely seen the amazing shells, either found clean and polished entirely or the beautiful jewellery that is made out of it, both found widely distributed in shops and on local markets. Very few visitors are probably aware that these slow-growing animals faced a heavy fishery pressure during the last decade and are nowadays a more and more disappearing resource. The fishery on Spondylus is still not regulated and consequently stocks appear to be severely overexploited. A detailed study of the ecology and population dynamics of Spondylus species is therefore urgently required to provide the information necessary for a sustainable management and thus protection of this ecologically and economically valuable resource.

History

The demand for Spondylus shells to manufacture the famous Spondylus jewellry severely threatens the populations of this slow-growing animalLa demanda de conchas de Spondylus para manufacturar la famosa joyería de Spondylus amenaza severamente las poblaciones de este animal de lento crecimiento

Typical Spondylus jewellry, using the wonderful colours of the small ring along the shell ends Típica joyería de Spondylus. Se aprovechan los bellos colores del estrecho anillo que se encuentra a lo largo del borde de las valvas

A fishermen can collect some 400-500 shells within 2 or 3 days of diving only, but the bivalve is becoming more and more scarce Un pescador puede llegar a recoger entre 400 y 500 conchas en solo 2 ó 3 días, pero este animal cada vez es más escaso

Spondylus serves as a host for a wide variety of epibiontsLos Spondylus sirven como huéspedes de una gran variedad de epibiontes.

Living Spondylus in a natural habitat. The arrow points at the gap between the two valves which sometimes is the only difference between the bivalve and a well overgrown stoneSpondylus vivo en su hábitat natural. La flecha indica el espacio entre las dos valvas, que a veces es la única diferencia a simple vista entre este bivalvo y una roca

Spondylus calcifer from the Ayangue areaSpondylus calcifer del área de Ayangue

These relatively “young” specimens are sold intact, as they still display the beautiful spines that disappear later in lifeEstos especímenes relativamente “jóvenes” se venden intactos, ya que aún conservan sus bellas espinas, que desaparecen con la edad

Spondylus princeps features a small attachment area, whereas Spondylus calcifer can be found attached to boulders and rocks with the whole left valve Spondylus princeps tiene una área de anclaje muy pequeña, mientras que Spondylus calcifer puede encontrarse adherido a grandes rocas usando todo el área de su valva izquierda

A typical Spondylus princeps with spinesTípico Spondylus princeps con sus características espinas

Belonging to the class of Bivalvia, the family Spondylidae (Gray, 1826) consists of only one genus: Spondylus (Linnaeus, 1758) with current estimates of different living species between 70 and 80, many of them under scientific revision. This family is closely related to the family Pectinidae (Scallops) with whom they share the complex eyes around the mantle and a relatively well developed nervous system. Spondylus is usually cemented to the substrate instead of using a byssus. Despite their abundance in the tropical oceans of the world, very little is known about basic biology and ecology of Spondylidae.