noun
parazoan
Technical term in zoology for a member of the subkingdom Parazoa, whose only extant representatives are sponges. Rare outside academic contexts.
側生動物は、海綿動物のみが現生する原始的な動物群である。
Parazoans are a primitive animal group whose only living members are the sponges.
海綿動物 refers specifically to sponges (Porifera), which are the only extant parazoans. 側生動物 is the broader taxonomic term for the subkingdom Parazoa.
From 側生 (そくせい, 'lateral growth' or 'parazoan') + 動物 (どうぶつ, 'animal'). The term is a direct calque of the taxonomic name Parazoa.