Squids Attract Mates with Stylish Ink: Heart Marks as Love Signals

TOKYO, Feb 14 (News On Japan) - A research group from the University of Tokyo and others has announced that squid, which are known to eject ink to confuse predators and escape, also use the ink in a courtship behavior to make themselves more conspicuous and appeal to females.

This is the first time such courtship behavior has been confirmed, and the research group hopes it will aid in the understanding of the evolution of animal communication.

Graduate students from the University of Tokyo, including Arata Nakayama, focused on a species of squid called the Gonatus squid, observing the males as they courted females by touching them with two special tentacles while ejecting ink. They found that the males would stroke the females with their tentacles for an extended period and emit small blobs of ink before finally spreading ink over a wide area to darken the background and then making their bodies shine white to court the females. According to the research group, this is the first time squid have been observed using ink for courtship behavior. Associate Professor Yoko Iwata of the University of Tokyo's Atmosphere and Ocean Research Institute said, "I was very surprised to find that squid, which have high intelligence, have repurposed ink originally used for escape for courtship behavior. Being able to immediately set the stage when they want to court is a significant advantage and will help us understand the evolution of animal communication."

The Gonatus squid, which measures about 12 centimeters in length, inhabits the sea at a depth of around 50 meters from southern Hokkaido to the Philippines, but its detailed ecology is still not well understood. The Aomori Prefectural Asamushi Aquarium, which was the first to successfully breed this species of squid in Japan, made headlines in 2019 when it captured footage of a male using its short tentacles to form a "heart mark" while courting a female. The latest research findings have come from continued observation, paying attention to the fact that the squid were also ejecting ink while forming the "heart mark" with their tentacles.

Source: NHK

Legionella Bacteria Found at Osaka Expo’s Quiet Forest and Water Plaza

Legionella bacteria have been detected in multiple locations at the Osaka-Kansai Expo site, prompting health and safety measures. According to the Japan Association for the 2025 World Exposition, seawater collected on June 3rd from the Water Plaza, where water shows are held, was found to contain Legionella bacteria at 20 times the guideline limit.

Japan's Annual Births Fall Below 700,000 for the First Time

The number of babies born in Japan in 2024 fell below 700,000 for the first time since recordkeeping began in 1899, highlighting the nation’s accelerating demographic crisis. According to population statistics released by the Ministry of Health, Labour and Welfare on June 4th, the number of births dropped to 686,061—down more than 40,000 from the previous year.

Convenience Stores Nationwide to Sell Government Rice in 1–2 kg Packs

Three major convenience store chains will soon begin selling government stockpiled rice in small packages of 1 to 2 kilograms. FamilyMart will start selling rice harvested in 2021—classified as old stock—at 20 locations in Tokyo and Osaka starting June 6th. The rice will be priced at 360 yen per kilogram, excluding tax, with plans for a nationwide rollout.

Cash Storage to Be Banned in Safe Deposit Boxes

Mitsubishi UFJ Bank and other institutions are moving to revise rules on the use of safe deposit boxes following a string of thefts, with the Japanese Bankers Association now working toward a ban on storing cash in these boxes.

Shigeo Nagashima, Symbol of Japan’s Golden Age of Baseball, Dies at 89

Shigeo Nagashima, one of Japan’s most iconic postwar figures and known as "Mr. Pro Baseball," has died at the age of 89, it was learned on June 3rd. A native of Chiba Prefecture, Nagashima helped define an era of professional baseball and became a national hero.

MEDIA CHANNELS

MORE Sci-Tech NEWS

Kyoto Researchers Launch Final Trial for Alzheimer’s Drug

Kyoto University's Center for iPS Cell Research and Application (CiRA) and pharmaceutical company Towa announced they began the final phase of clinical trials in May, aiming to treat Alzheimer’s disease using an existing medication.

Shizuoka Clears Final Water Hurdle for Linear Project as Implementation Phase Begins

A Shizuoka Prefecture expert panel overseeing environmental issues linked to the Linear Chuo Shinkansen project met on June 2nd and concluded all discussions related to water resources, ending over a decade of debate. Deputy Governor Hiraki described the outcome as "a major step forward."

JAXA Prepares New Unmanned Supply Craft for ISS Delivery

The Japan Aerospace Exploration Agency (JAXA) on June 2nd unveiled its new unmanned cargo spacecraft, the HTV-X, at the Tanegashima Space Center in Kagoshima Prefecture. Designed to transport supplies to the International Space Station (ISS), the HTV-X is undergoing final preparations for launch within fiscal 2025.

Japan’s Healthcare in Crisis, Doctors Overworked as Research Time Dwindles

Amid mounting financial strain and work reform policies, Japan’s university hospitals are struggling to maintain the quality of their medical research, threatening the future of healthcare in the country. A recent survey of approximately 3,000 physicians working in university hospitals revealed that 60% spend less than five hours a week on research, with 22% reporting zero research time. The main reason: they are simply too busy with clinical duties to conduct research.

次世代クラウド保護 ― 「あると便利」から「不可欠」へ

2025年には、クラウドに対する侵害のうち60％以上が設定ミスに起因していました。企業がスケーラビリティやコスト削減のためにクラウドを活用すればするほど、それに伴って新たなセキュリティリスクにさらされる可能性も高まります。

World’s Largest Butterfly Fossil Discovered in Japan

A butterfly fossil discovered 37 years ago in Shinonsen, Hyogo Prefecture, and kept in a local museum has been identified as a new species and the largest butterfly fossil ever found globally.

Nissan Unveils Latest e-POWER Hybrid

Nissan has unveiled the latest model of its proprietary hybrid system, e-POWER, by showcasing the updated Qashqai equipped with the technology. The company says it has significantly improved fuel efficiency during high-speed driving—an area that had previously been seen as a challenge.

How Japanese iPhone Users Are Optimizing Their Devices in 2025

In Japan, iPhones make up over 60% of the market share. The pretty design and the reliability have been ͏incorporated into the market because Japanese people consider it a daily need due to apps and features.

< 2 3 4 5 >