hexactin

hexactin

[hek′sak·tən]
(invertebrate zoology)
A spicule, especially in Porifera, having six equal rays at right angles to each other.
References in periodicals archive ?
min avg L dermal hexactin distal ray 24 0.037 0.252 0.151 L dermal hexactin tangential ray 25 0.104 0.185 0.143 L dermal hexactin proximal ray 18 0.141 0.481 0.310 L atrial pentactin tangential ray 6 0.278 0.414 0.335 L atrial pentactin ray directed 4 0.352 0.444 0.389 inside body D drepanocome 12 0.059 0.081 0.074 d drepanocome 12 0.015 0.019 0.017 D floricome 25 0.089 0.118 0.105 d floricome 25 0.015 0.030 0.020 D spiny hexactin 25 0.178 0.266 0.220 D pappocome 25 0.259 0.333 0.300 d pappocome 1 0.016 0.016 0.016 D large discohexaster 2 0.118 0.141 0.130 d large discohexaster 2 0.022 0.036 0.029 D small discohexaster 11 0.032 0.065 0.048 d small discohexaster 11 0.014 0.020 0.017 D discohexactin 3 0.185 0.215 0.195 Holotype std nn min.
Choanosomal spicules are principalia (stauractins, some tauactins, and diactins), rare pinular hexactins, and additional spicules (comitalia: smaller stauractins, tauactins, diactins, and, maybe, pentactins).
Dermalia are hexactins smaller than that described above; they have distal rays lanceolate, lanceolate-pinular, or stout, similar to other rays of these spicules.
Spicules of this type are numerous: drepanocomes, floricomes, pappocomes, large and small discohexasters, and spiny hexactins; discohexactins were unique (found in the holotype only).
The simple zoological diagnosis of Heterochone is: Aphrocallistidae with atrialia as pinular hexactins.
Diagnosis.-Aphrocallistidae with atrialia as pinular hexactins.
1A, arrows); wall 1 cm thick penetrated by radial diarhyses (skeletal channels of dictyonal framework) passing from dermal to atrial surface; dermal surface entirely covered by rectangular lattice of loose pinular hexactins of 149-183-235 [micro]m mesh (Fig.
Megascleres: Dermal and atrial pinular hexactins (Fig.