Creseis acicula (Rang, 1828)

Description

A holoplanktonic shelled pteropod with a slender, transparent, needle-shaped shell reaching about 25 mm in length. Body white and transparent, very slender and elongate; the wing-like fin lobes are small and oblong, the visceral mass barely visible through the body. Shell more transparent than that of related Creseis, slender in proportion, more or less flexuous, with a very small aperture and a smooth surface. The original specimens reported by Rang were 12 mm long.

Distribution

Cosmopolitan in tropical and warm-temperate seas. Rang's original record cited "the Ocean and the Indian Sea". Mass strandings on Japanese coasts in spring–early summer (April–July) when blooms drift inshore on the Kuroshio Current; beaches can become covered with the transparent needle-like shells.

Etymology

The specific epithet acicula is the Latin for "small needle" (diminutive of acus, "needle"), in reference to the slender needle-shaped shell.

Remarks

Originally described as Creseis acicula by Rang in "Notice sur quelques Mollusques nouveaux appartenant au genre Cléodore, et établissement et monographie du sous-genre Creseis" (Annales des Sciences naturelles, Paris 13: 318, sp. 9, pl. 18 fig. 6, 1828), in the same paper that erected the sub-genus Creseis. Creseis was raised to full genus rank subsequently.

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References

• Creseis acicula, Rang S. (1828). Notice sur quelques mollusques nouveaux appartenant au genre Cléodore, et établissement et monographie du sous-genre Créseis. Annales des Sciences Naturelles, Paris, 13: 302-319, pls. 17-18.
• ウキヅノガイ Cresies acicula (Rang, 1828), 奥谷喬司 (2016). わが国近海に見られる浮遊性巻貝類―IV. 有殻翼足類 (1)：カメガイ科のウキビシガイ亜科・ウキヅツガイ亜科. うみうし通信 91: 8-9.
• Creseis acicula, Gosliner, T. et al. (2023). Southern African Sea Slugs. Southern Underwater Research Group Press, 7 Blackwood Drive, Hout Bay 7806, Cape Town, South Africa.