📸 PhotoPhoto: Comingio Merculiano (1845–1915) in Jatta Giuseppe · Public domain · Wikimedia Commons Source
Greater argonaut
Argonauta argo (Greater argonaut · アオイガイ)
💡 Everyday Comparisons for Size, Mass & Speed
- 💡 A female's 30 cm shell length is the same length as a single 30 cm ruler (Comparison).
- 💡 Males are 1.5–2 cm long, smaller than a Korean 500-won coin (diameter about 2.65 cm) (Comparison).
- 💡 It is sold in fish markets in India and Japan, and the shell is popular with collectors for its beauty and fragility (ADW).
Reference standards: coach bus ~12 m, mid-size car ~4.9 m, compact car ~1 t, basketball hoop 3.05 m, credit card 8.56 cm.
📖 1. Overview
The greater argonaut is an octopus that drifts in surface waters of tropical and temperate seas. Only the female makes a thin, boat-shaped shell.
🦴 2. Anatomy & Morphology
Females use secretions from their largest arms to form a flexible boat-shaped shell around 30 cm long, whereas males are shell-less dwarfs only 1.5–2 cm long. Females trap air gathered at the sea surface inside the shell to keep from sinking.
🔍 3. Ecology & Behavior
It lives solitarily and feeds on plankton and small organisms near the surface. The shell made by the female also serves as an egg case.
🇰🇷 4. Connection to Korea
It is listed as 'Jogaenakji' (Korean name) in the National List of Species of Korea, and in Korea it has been recorded from Gangwon-do and Jeju Island.
📚 Sources & References
- • IUCN Red List LC (2014) — https://www.iucnredlist.org/species/163080/969616
- • IUCN Red List category LC — latest assessment at iucnredlist.org
- • marinespecies.org — aphia.php
- • iucnredlist.org — 969616
- • 국가생물종목록(국립생물자원관) ktsn 120000044093 — https://species.nibr.go.kr/home/mainHome.do?cont_link=009&subMenu=009002&contCd=009002&ktsn=120000044093
- • wikidata.org — Q39514
- • commons.wikimedia.org — File:Argonauta argo Merculiano.jpg
- • sealifebase.se — Argonauta-argo.html
- • species.nibr.go.kr — mainHome.do
- • animaldiversity.org — Argonauta argo
- • Silhouette: PhyloPic — Comingio Merculiano · CC0 1.0
Recorded dimensions are widely cited representative estimates from public literature and may vary by study or specimen.