Soa-hî sī kut hē-thóng choân nńg-kut, sin-khu liû-soàⁿ-hêng (streamlined) ê hî, sio̍k tī Selachimorpha chhiau-ba̍k. In khò 5~7 ê hî-chhi-li̍h (gill slits) ho͘-khip. In ū 1 têng chin-phoê sió-khí (dermal denticles) khàm tī phoê-hu goā-bīn pó-hō͘ kiam ī-hông thâng kià-seⁿ, mā ū kái-siān liû-thé-le̍k-ha̍k (fluid dynamics) ê lō͘-iōng. In ê chhùi-khí ū koh seⁿ ê châi-tiāu. Soa-hî sī siōng chia̍p hō͘ lâng gō͘-kái ê 1 chióng lia̍h-chia̍h tōng-bu̍t (predator); nā m̄ sī siū tio̍h ui-hiap, in khêng-si̍t hán-tit kong-kek lâng.
