Keishu Asada
@cephwarden.bsky.social
A warden of Sand Quentin.
Videographer and photographer, mostly of marine wildlife. Marine Fieldwork Specialist at the Okinawa Institute of Science and Technology (OIST), Marine Science Section.
Videographer and photographer, mostly of marine wildlife. Marine Fieldwork Specialist at the Okinawa Institute of Science and Technology (OIST), Marine Science Section.
Ctenophores glimmering like alien angels
February 10, 2026 at 10:00 AM
Ctenophores glimmering like alien angels
As someone who can be frightfully forgetful, this news feels like it has ominous suggestions as to how much my faculties are propped up purely by coffee
Coffee or tea may lower your risk of dementia — if it's got caffeine and you drink a moderate amount each day. www.nytimes.com/2026/02/09/h...
2 to 3 Cups of Coffee a Day May Reduce Dementia Risk. But Not if It’s Decaf.
www.nytimes.com
February 10, 2026 at 1:39 AM
As someone who can be frightfully forgetful, this news feels like it has ominous suggestions as to how much my faculties are propped up purely by coffee
This tiny brittlestar is impossible to see when it stops moving
February 9, 2026 at 11:09 PM
This tiny brittlestar is impossible to see when it stops moving
Photos of the wobbegong. Impressive how well it blends in when it holds still.
February 9, 2026 at 10:06 AM
Photos of the wobbegong. Impressive how well it blends in when it holds still.
A rare reward exploring at the crack of dawn: A wobbegong shark cruising out of the morning gloom
February 8, 2026 at 8:35 AM
A rare reward exploring at the crack of dawn: A wobbegong shark cruising out of the morning gloom
First dive of the year, and there's a first time for everything: Although I've seen them washed up on beaches many times, this is the first time I've seen a bluebottle (Portuguese man o' war) in the water. Like a blue balloon in the sky (filled with carbon monoxide and has a stinging 'string')
January 10, 2026 at 9:50 AM
First dive of the year, and there's a first time for everything: Although I've seen them washed up on beaches many times, this is the first time I've seen a bluebottle (Portuguese man o' war) in the water. Like a blue balloon in the sky (filled with carbon monoxide and has a stinging 'string')
A squid beneath the waves. From my last dive of 2025.
December 21, 2025 at 5:12 AM
A squid beneath the waves. From my last dive of 2025.
Scorpionfish hiding
December 17, 2025 at 10:32 PM
Scorpionfish hiding
A old spent bullet casing. Not sure if it dates back to the Battle of Okinawa but it's fairly unlikely for one to end up here otherwise.
December 16, 2025 at 10:41 PM
A old spent bullet casing. Not sure if it dates back to the Battle of Okinawa but it's fairly unlikely for one to end up here otherwise.
Squid in sunshine
December 10, 2025 at 10:47 PM
Squid in sunshine
A pteropod in the sunlight. Maybe like a dream where your ice cream cone is flapping away
December 10, 2025 at 10:53 AM
A pteropod in the sunlight. Maybe like a dream where your ice cream cone is flapping away
A broadclub cuttlefish (Ascarosepion latimanus) showing what I call the 'angry bull' signal to another cuttlefish. It flicks its arms from side to side as a wave of dark color flashes over them, and it releases a small puff of ink. Sadly with its back mostly turned to me. 1/2
December 9, 2025 at 10:09 AM
A broadclub cuttlefish (Ascarosepion latimanus) showing what I call the 'angry bull' signal to another cuttlefish. It flicks its arms from side to side as a wave of dark color flashes over them, and it releases a small puff of ink. Sadly with its back mostly turned to me. 1/2
Sunbeams and sealife
December 8, 2025 at 10:58 PM
Sunbeams and sealife
The quiet storm of fish under the pier
December 8, 2025 at 11:08 AM
The quiet storm of fish under the pier
Since Duolingo decided to basically brick its app with the new 'energy' system that won't let you get through three lessons in a day, does anyone know any decent Duolingo alternatives?
October 14, 2025 at 1:35 PM
Since Duolingo decided to basically brick its app with the new 'energy' system that won't let you get through three lessons in a day, does anyone know any decent Duolingo alternatives?
Okinawa had its hottest September at 1.6C above the average. I filmed this mass coral bleaching last year, but didn't have the heart to share. Total annihilation of the first few meters of depth. This stuff happens before our eyes, and yet people who think it isn't real keep gaining power.
October 2, 2025 at 10:24 AM
Okinawa had its hottest September at 1.6C above the average. I filmed this mass coral bleaching last year, but didn't have the heart to share. Total annihilation of the first few meters of depth. This stuff happens before our eyes, and yet people who think it isn't real keep gaining power.
Yajaagama cave: Turning back at the clearing and heading out.
October 1, 2025 at 11:24 PM
Yajaagama cave: Turning back at the clearing and heading out.
Yajaagama cave: Human bones. The cave is a historical burial ground with many broken urns. The remains are placed in several places, like the clearing at the end. Apparently the locals are fine with leaving them be.
October 1, 2025 at 11:19 PM
Yajaagama cave: Human bones. The cave is a historical burial ground with many broken urns. The remains are placed in several places, like the clearing at the end. Apparently the locals are fine with leaving them be.
The exit of Yajaagama. You're supposed to turn around at this clearing, although the cave actually continues just beyond it. You can see that this clearing was once part of the cave that has collapsed.
October 1, 2025 at 11:17 PM
The exit of Yajaagama. You're supposed to turn around at this clearing, although the cave actually continues just beyond it. You can see that this clearing was once part of the cave that has collapsed.
Parts of the cave look like it's melting. The dark specs here are inse.. cts.A species or subspecies of cave cricket (クメカマドウマ). These are one of the most common things in the cave, although I couldn't find much information on them.
October 1, 2025 at 11:10 PM
Parts of the cave look like it's melting. The dark specs here are inse.. cts.A species or subspecies of cave cricket (クメカマドウマ). These are one of the most common things in the cave, although I couldn't find much information on them.
Yajaagama cave: Close to the exit, there were this endemic subspecies of ground gecko, Goniurosaurus kuroiwae yamashinae. Beautiful stripes.
October 1, 2025 at 11:07 PM
Yajaagama cave: Close to the exit, there were this endemic subspecies of ground gecko, Goniurosaurus kuroiwae yamashinae. Beautiful stripes.
Yajaagama cave: Parts of the cave have glittering minerals. Sometimes they form beautiful little terraced pools.
October 1, 2025 at 11:06 PM
Yajaagama cave: Parts of the cave have glittering minerals. Sometimes they form beautiful little terraced pools.
Yajaagama cave: In many places it looked like there were veins of gold or some such mineral, but up close they turn out to be growths of lichen, covered in little droplets of water so they glitter.
October 1, 2025 at 10:51 AM
Yajaagama cave: In many places it looked like there were veins of gold or some such mineral, but up close they turn out to be growths of lichen, covered in little droplets of water so they glitter.