Recent new jellyfish species include Physalia mikazuki, a "crescent helmet" Portuguese man-of-war found in Japan (2025), and Tripedalia maipoensis, a fast-swimming box jellyfish with 24 eyes found in Hong Kong (2023), highlighting climate change impacts and undiscovered diversity in marine waters. Another recent discovery is Santjordia pagesi, a rare red-bellied jellyfish from a new genus and subfamily, found in the deep sea.
Researchers in Japan Discover New Jellyfish Species Deserving of a Samurai Warrior Name. A student-led research group from Tohoku University has discovered a new species of the venomous Physalia (commonly known as Portuguese man-of-war) that has never been seen before in northeast Japan.
The study, published in Frontiers in Marine Science (Marine Molecular Biology and Ecology) on October 30, 2025, presents the first formal description of a Physalia species from Japan.
Yes, lion's mane jellyfish stings are painful and can cause burning, redness, and swelling, though they are rarely fatal to healthy individuals, but can trigger severe allergic reactions, so it's crucial to get medical help for significant reactions or large area stings. Their long, fine tentacles can easily break off and deliver venom, requiring immediate first aid like applying hot water and seeking professional care for severe symptoms like chest pain or difficulty breathing.
If this mechanism were to occur indefinitely, Turritopsis dohrnii would never die of natural causes, earning it the nickname “immortal.” However, as a species within an ecosystem, it is still subject to death from predators, infections, etc.
Turritopsis dohrnii, the so-called "immortal jellyfish," can hit the reset button and revert to an earlier developmental stage if it is injured or otherwise threatened. Like all jellyfish, Turritopsis dohrnii begins life as a larva, called a planula, which develops from a fertilized egg.
Turritopsis dohrnii, also known as the immortal jellyfish, is a species of small, biologically immortal Medusozoa (jellyfish) found worldwide in temperate to tropic waters.
The lion's mane jellyfish Cyanea capillata is the largest jellyfish in the world. With its numerous tentacles that can reach a record length of 36.6 metres, this jellyfish is larger than a blue whale!
Chrysaora melanaster , one of the largest jellyfish commonly found in the Arctic, swims underneath the Arctic ice. Its tentacles can stretch to more than 3 meters long and pack a mean sting for humans.
The research, published in the international journal Toxins shows that the best first aid for a lions mane sting is to rinse with vinegar (or the commercial product Sting No More® Spray) to remove tentacles, and then immerse in 45°C (113°F) hot water (or apply a heat pack) for 40 minutes.
The creature that is 98% water is the jellyfish, a gelatinous marine invertebrate whose bell-shaped body is largely composed of water, giving it a translucent, blob-like appearance and low energy needs for growth. This high water content (sometimes cited as 95-98%) allows them to be buoyant and drift, making them an evolutionary success story in the oceans, according to NOAA's National Ocean Service and National Geographic.
Stygiomedusa gigantea, commonly known as the giant phantom jelly, is the only known species in the monotypic genus of deep sea jellyfish, Stygiomedusa. It is in the Ulmaridae family.
Suzy's adult brother is in a same-sex relationship, and he and his boyfriend occasionally visit Suzy and her mom. Suzy mentions a time she saw through the windshield a quick kiss between them before they backed out of the driveway and drove to the movies. A spot of blood is mentioned in the context of a first period.
This is because jellyfish are about 95 percent water. Lacking brains, blood, or even hearts, jellyfish are pretty simple critters.
Oxford, UK — [29 October, 2025] – Thirty previously unknown deep-sea species, including a carnivorous “death-ball” sponge, have been confirmed from one of the most remote parts of the planet by The Nippon Foundation–Nekton Ocean Census and collaborators.
Halitrephes maasi is the scientific name of the firework jellyfish. They are among the rarest and prettiest species. They have very thin tentacles that reflect light, which appear like a firework. Moreover, these tentacles are frilled and appear like stars around the moon.
The simplest swimming animals on Earth, jellyfish lack bones, blood, a heart, and even a brain.
The Pink Lion's Mane Jellyfish's disc-shaped bell can be over 1 m across and its trailing tentacles can reach more than 10 m in length. These tentacles are very fine and difficult to see.
Moon jellies are not threatened or endangered but can serve as an indicator of marine ecosystems out of balance.
The Australian box jellyfish is considered the most venomous marine animal. They may not look dangerous, but the sting from a box jellyfish could be enough to send you to Davy Jones's locker-a watery grave, that is.
The largest jellyfish ever recorded was a lion's mane jellyfish found in 1870 off Massachusetts Bay. Its bell measured 2.3 meters across, and its tentacles stretched 36.5 meters, which is even longer than a blue whale. This earned it the Guinness World Record for the longest animal.
This colorful jelly has a very toxic sting, but reports of human fatalities are few. It's considered a giant jelly — its bell can reach about three feet (1 m) in diameter and its tentacles can grow to more than 100 feet (30.5 m) long.
The hydrozoan Turritopsis dohrnii, an animal about 4.5 millimetres wide and tall (likely making it smaller than the nail on your little finger), can actually reverse its life cycle. It has been dubbed the immortal jellyfish.
Even so, scientists have uncovered evidence these creatures have been living in our Ocean for at least 500 million years! In fact, it's likely that their lineage goes back even as far as 700 million years – possibly even longer. That makes them almost three times older than the first known dinosaurs.
The tubeworm Escarpia laminata that lives in deep sea cold seeps regularly reaches the age of between 100 and 200 years, with some individuals determined to be more than 300 years old. Some may live for over 1,000 years.