Sponges of the New Caledonian lagoon - IRD

Order
Haplosclerida
T hese
Family
Chalinidae
sponges have their main skeleton formed of simple diactinal spicules,
usually oxeas of one type and size, although thinner developmental forms may
occur. Spicules can be modified to strongyles or strongyloxeas.
In the Families Chalinidae, Niphatidae and Callyspongiidae, spicules are often embedded
in spongin fibres in uni- or multispicular tracts. The skeletal arrangement is neat and
regular, not dense or crowded. This skeleton often forms an isodictyal triangular
reticulation but spicules and fibres also form triangular, rectangular or polygonal meshes.
In some groups spongin fibres are well developed whereas in others they are less well
developed, where spicules are bonded together by variable quantities of collagenous
spongin. Microscleres may include c- and s-shaped sigmas, frequently with a central (or
centrangulate) kink, and sometimes smooth toxas or microxeas. Where known, species
of the families Chalinidae, Callyspongiidae and Niphatidae are viviparous, incubating
their young.
Sponges belonging to the Families Petrosiidae and Oceanapiidae are typically massive,
vase-shaped or volcano-shaped, sometimes repent, or bulbous, and fistulous. Their texture
is characteristically stony, brittle, reflecting that in most species siliceous spicules are
dominant over spongin. The external surface has a smooth appearance where the surface
skeleton is an isotropic reticulation of single spicules or spicule tracts forming a crust. The
main choanosomal skeleton is more or less a regular isotropic reticulation composed of
multispicular tracts bound together with minimal collagen or light spongin fibres, usually
forming large oval meshes. Microscleres may include microxeas, microstrongyles, sigmas
and toxas but they are not common. Reproduction is oviparous, where eggs and sperm
are released into the water and larvae develop externally to the parent.
Haplosclerida are particularly abundant on coral reefs, including those of New Caledonia
and the Great Barrier Reef, living in full light amongst hard corals as well as in many
cryptic habitats and in between the reefs on the seabed. They generally do not attain
massive proportions, except the Petrosidae and are frequently fans, tubes, branches or
ramose morphology. The genera Col/yspongio, HoJic/ano, Niphotes and Gel/iades are
common.
Haliclona cymaeformis
(Esper, 1794)
137
The Siliceous
Sponges