海參(can)(can)的內骨(gu)骼多(duo)(duo)不發達,變為須用顯微(wei)鏡才能看見的許多(duo)(duo)微(wei)小(xiao)石灰質骨(gu)片(pian)(pian)(pian)埋沒于外皮(pi)之(zhi)下(xia),數(shu)目一般都(dou)很多(duo)(duo)。觀(guan)察骨(gu)片(pian)(pian)(pian)應作些處理,最(zui)(zui)簡單的方法是取一小(xiao)片(pian)(pian)(pian)皮(pi)膚,置于玻片(pian)(pian)(pian)上(shang),然后滴1-2滴次氯(lv)酸鈉(na)溶(rong)液(ye)(ye)于皮(pi)膚上(shang),1-2min,次氯(lv)酸鈉(na)溶(rong)液(ye)(ye)會把皮(pi)膚組織(zhi)腐蝕(shi)掉(diao),而剩下(xia)骨(gu)片(pian)(pian)(pian),再加1-2滴蒸餾水,蓋(gai)(gai)上(shang)蓋(gai)(gai)玻片(pian)(pian)(pian),置于顯微(wei)鏡之(zhi)下(xia)便(bian)能觀(guan)察清楚。海參(can)(can)骨(gu)片(pian)(pian)(pian)形(xing)(xing)狀美(mei)麗而多(duo)(duo)變,是海參(can)(can)分類(lei)最(zui)(zui)重要的依據,常見的骨(gu)片(pian)(pian)(pian)有桌(zhuo)形(xing)(xing)體、扣狀體、桿狀體、穿孔板、花紋樣體、輪(lun)形(xing)(xing)體和(he)錨形(xing)(xing)體等(deng)。海參(can)(can)骨(gu)片(pian)(pian)(pian)數(shu)量(liang)很多(duo)(duo),有人計算過1個丑(chou)海參(can)(can)有約2000萬個骨(gu)片(pian)(pian)(pian)。
海參(can)咽(yan)部圍繞一環鈣質骨板,稱(cheng)為石(shi)灰(hui)環,由(you)10塊骨板組(zu)成,5個輻(fu)位(wei)的(de)骨板,稱(cheng)輻(fu)片,5個間輻(fu)位(wei)的(de)骨板,稱(cheng)間輻(fu)片。石(shi)灰(hui)環是海參(can)特有的(de)器官,它(ta)可能(neng)和海膽的(de)亞里斯(si)多德提燈同源。石(shi)灰(hui)環形態在海參(can)分類上也很重要(yao)。