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

Feb 14, 2024 | News On Japan

TOKYO - 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

Typhoon No. 25 Moves Away From Japan Into Pacific

Typhoon No. 25 was moving away from Japan over waters to the east early on September 22, bringing an end to rainfall across the Kanto region while remaining a strong storm as it tracked northeast at 45 kilometers per hour at 3 a.m.

Rail Links to Narita Airport Disrupted as Typhoon Damage Lingers

Severe transport disruption continued across Chiba Prefecture on the morning of September 22 even as Typhoon No. 25 moved away from Japan, with major JR lines still suspended, rail access to Narita Airport disrupted by river flooding, highways closed across the Boso Peninsula and thousands of travelers dealing with the aftermath of the previous day's cancellations.

Japan Takes 12 Medals on Asian Games Day 3

Japan collected another 12 medals on Day 3 of the Aichi-Nagoya Asian Games on September 21, with 17-year-old swimmer Shin Ohashi and karateka Kakeru Nishiyama winning gold, while the host nation also advanced strongly in women's volleyball, baseball, soccer, handball and hockey.

Japan's Elderly Population Hits Record 29.6%

People aged 65 and older accounted for a record 29.6% of Japan's population in 2026, the highest proportion among major countries worldwide, while the number of elderly people in employment also reached an all-time high as Japan marked Respect for the Aged Day on September 21.

Emperor and Empress Watch Asian Games Basketball

Emperor Naruhito and Empress Masako watched Japan defeat Kazakhstan in a women’s basketball preliminary-round game at the 20th Asian Games in Nagoya.

MEDIA CHANNELS

MORE Sci-Tech NEWS

Rare Pod of About 50 Dolphins Spotted in Seto Inland Sea

A rare pod of around 50 dolphins was spotted swimming through the Seto Inland Sea off Ozu, Ehime Prefecture, with dozens of dorsal fins repeatedly breaking the surface as the animals moved together.

Cybercab Arrives in Japan

Tesla unveiled its Cybercab in Japan for the first time on September 11, showcasing an AI-powered autonomous taxi designed without a steering wheel or pedals.

Footage Shows Tokyo Flood Control Tunnel After Heavy Rain

Large volumes of floodwater poured into the Metropolitan Area Outer Underground Discharge Channel in Kasukabe, Saitama Prefecture, following heavy rain on September 7, prompting the massive underground flood-control facility known as the "Underground Temple" to go into operation.

Lights Out for Fluorescent Lamps

Fluorescent lamps that have illuminated Japanese homes and workplaces for decades are approaching the end of production, with Panasonic preparing to wind down a business it has operated since 1951 while experts warn that incorrectly replacing some fixtures with LEDs could create a fire risk.

Dry Fog Finds New Uses in Industry, Farming and Tourism

Osaka-based spray nozzle maker IKEUCHI is expanding applications for its proprietary "Dry Fog," an ultra-fine mist that can cool, humidify and create visual effects without leaving surfaces wet, with the technology now being used in factories, livestock farming, crop cultivation and tourist attractions in Japan and overseas.

Japan Moves to Commercializing Low-Power Optical Computing

Japanese companies are moving closer to commercializing photonics-electronics convergence technology that replaces part of conventional electrical data transmission with optical signals, potentially allowing huge volumes of data to move with lower latency while sharply reducing power consumption as artificial intelligence drives rapid growth in electricity demand from data centers.

Just 27 Centimeters Could Dramatically Reduce Power Consumption

A new generation of optoelectronic integration technology developed over four decades by Japanese companies is moving closer to commercialization, offering a way to transmit huge volumes of data with low latency while sharply reducing the electricity consumed by data centers as artificial intelligence drives explosive growth in computing demand.

CameraJet Connects Cleaning Coaching and Privacy

Dyson CameraJet™ turns the smart toothbrush into an active sensing product, making useful feedback and clear privacy design part of the same engineering brief.

< 2 3 4 5 >