Question

Scypha (Sycon) belongs to
(a) Calcarea
(b) Hexactinellida
(c) Demospongiae
(d) Hyalospongiae

Answer 1

Hint: These sponges are thin, up to 7.5 cm long and 2.5 to 7.5 cm long, and are tubular in form and mostly white to cream in colour. They are known as "Pineapple" or "Q-Tip" sponges to aquarium hobbyists and are regular "hitchhikers" mistakenly brought in.

Complete answer:
A genus of calcareous sponge belonging to the Sycettidae family is Sycon ciliatum. Sponges are marine invertebrates sandwiched between two layers of cells, with a jellylike mesohyl. They are philtre feeders that through their construction sustain a flow of water that passes through wide openings called oscula. Composed of rigid spicules, they have a delicate skeleton. The Amphiblastula is a Scypha larva. Sycon, recently called Scypha, is the marine habitat of the simplest type of sponge. It stays bound to rocks on the seashore just below the tide line. A mixture of shades of grey and light brown is the colour of a live specimen. Scypha belongs to the subclass Galcoronea, phylum Porifera, class Calcarea.
A solitary/colonial life is led by Sycons. These marine entities, such as shells and rocks of corals and molluscs, are found attached to the strong substratum. Within this genus, there are various species of sponges that do not possess the propensity to prosper deeper in the water. In slow-wave activity and low tides, Sycons appear to survive well. They are present between hydroids, bryozoans, and other entities on the bottom of rocks in comparatively protected areas. Some emerge as marine algae too.

Additional information:
Demospongiae (Demospongiae; Porifera phylum)- A genus of sponges found both in the marine and freshwater environments. They have the body structure of a leucon. A skeleton can form both silica spicules and organic fibres, but skeletal support may be missing in primitive forms. This is the largest group of sponges in the Cambrian, and it appeared first.
Sponges with a skeleton consisting of four or six-pointed silica sponges, also referred to as glass sponges, are hexactinellid sponges. They are basically classified in the phylum Porifera together with other sponges, but some scientists believe them sufficiently distinct to be deserving of their own phylum, Symplasma.
Hyalospongiae is a Porifera class consisting of 6-rayed silica sponges, no surface epithelium, and choanocytes confined to finger-shaped chambers.

So, the correct answer is ‘Calcarea’.

Note:
All three sponge body plans are constituted as asconoid, syconoid, and leuconoid within the class of Calcarea. Calcareous sponges are usually thin, with a height of less than 10 cm (3.9 in and drab colour). A few brightly coloured species are also recognised, however. Calcareous sponges range from vase-shaped radially symmetrical body types to colonies made up of thin tube meshwork or irregular massive shapes. Either a mesh or honeycomb arrangement is available for the skeleton.