Poecillastra compressa (Bowerbank 1866)

“ECIONEMIA COMPRESSA, Bowerbank.

Sponge. Elevated on a short compressed pedicel, mass much compressed, surface even, smooth. Oscula simple, dispersed, small. Pores inconspicuous. Dermal membrane abundantly spiculous; tension spicula acerate or inflato-acerate, entirely incipiently spined, rather slender, numerous; retentive spicula attenuato­stellate, large; and elongo-attenuato stellate, small, and very numerous. Connecting spicula attenuato­patento-ternate, radii long and rather slender, shaft rather short. Skeleton. Spicule acerate, rarely acu­ate, large, and long. Interstitial membranes abun­dantly spiculous; spicula the same as those of the dermal membrane.

Colour.—Light gray.

Habitat—Shetland, Mr. C. W. Peach.

Examined.—In the dried state.

I am indebted to my friend Mr. Peach for this interesting specimen; the first British species I have seen of the genus. It was dredged by Mr. J. Gwyn Jeffrey, in 1864, and preserved for me by the donor, who accompanied the expedition. The sponge is in excellent preservation.

It is three and half inches in height; two and three quarters in breadth, within about an inch of the distal extremity, and its greatest thickness is about four lines; the height of the pedestal is three fourths of an inch, and its breadth nearly the same; and there are two lateral lobes of the sponge, which each extend downwards to about half the length of the pedestal, their inner margins being nearly in contact with its thin edges.

The most distinctive characters in this species are those of the spicula of the dermal and interstitial membranes, and the tension spicula especially so; the incipient spina­tion is common to them all, but the central inflation of the shaft is not equally prevalent; the greater number of them, perhaps, may be said to be deficient in that character, while in the other portion it is well developed, and always near the middle of the shaft. In many parts of the mem­branes, they are exceedingly numerous, and are always irregularly dispersed. The difference between the larger and the smaller stellate spicula in size is very considerable; the former are usually simply stellate or slightly elongated, while the latter appear always to be decidedly elongo-stellate. A satisfactory definition of these spicula requires a linear power of five or six hundred.

The connecting spicula are not very numerous, and are samewhat variable in size, their radii are often quite half the length of the shaft. I could not detect any recurvo­ternate spicula among them.”

(Bowerbank, 1866)

Poecillastra compressa is 'n sponsspesie in die taksonomiese indeling van die Demospongiae (gewone sponse). Die liggaam van die spons bestaan uit kieselnaalde en sponginevesels en is in staat om baie water op te neem.

Die spons behoort tot die genus Poecillastra en tot die familie Pachastrellidae. Die wetenskaplike naam van die spesie is die eerste keer geldig gepubliseer in 1866 deur Bowerbank.

Poecillastra compressa adalah spesies spons yang tergolong dalam kelas Demospongiae. Spesies ini juga merupakan bagian dari kelas Demospongiae, filum Porifera, subregnum Parazoa, dan kingdom Animalia.

Seperti spons pada umumnya, spesies ini memiliki tubuh yang berpori dan permukaan yang keras seperti batu. Selain itu, Poecillastra compressa juga dapat menyerap oksigen dari air melalui proses difusi.