Hyselodoris festiva (English spelling) Hyselodorisfestiva

...These horns are what gave them the name sea slug. Some species, such as the blue sea slug Hyselodoris festiva (illustration), have a smooth blue surface, while others, such as the silver sea slug Aeolidiella takanosimensis (illustration), have many projections lined up on their backs, like a horn. The centipede Melibe vexillifera (illustration) has particularly large projections on its back, which are easily torn off but can regenerate. Some species have feather-like gills surrounding the anus at the rear of their backs.

*Some of the terminology that mentions "Hyselodoris festiva" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…これを角に見立ててウミウシと名付けられた。　体表はアオウミウシHyselodoris festiva（イラスト）のように青色で滑らかな種もあるが，またミノウミウシAeolidiella takanosimensis（イラスト）のようにみのを着たように背上に多くの突起が並んだ種もあり，ムカデメリベMelibe vexillifera（イラスト）は背上の突起がとくに大きく，ちぎれやすいが再生もする。背上後方の肛門のまわりを羽状のえらが取り囲む種もある。…

※「Hyselodoris festiva」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報