Portuguese man-o-war

A Portuguese man-of-war (Physalia physalis) washed up on a beach. Photo by Dr. Alex Mustard, more can be found at www.amustard.com

Domain: Eukarya
Kingdom: Animalia
Phylum: Cnidaria
Class: Hydrozoa
Order: Siphonophorae
Family: Physaliidae
Genus: Physalia
Species: Physalia physalis

It’s summer time, the time of year I get to listen to the “jellyfish invasion.” Now, don’t get me wrong; jellies are increasing in number, and there are concerns about their large populations. However, Portuguese man-o-wars are not jellyfish—they’re siphonophores!

Siphonophores are the misunderstood cousins to jellyfish, especially Physalia physalis. Jellyfish are typically a single individual with a polyp stage. Siphonophores are a colony of individual organisms called polyps, and each group of individuals does a specific job for the colony.

Portuguese man-o-wars are made up of four separate polyps: the sails, the tentacles, the digestive organs, and reproductive system. Imagine that you and three of your clones, called zooids, live in an RV together. You are in charge of driving the RV, one clone is in charge of gathering food to feed everyone, one is the cook, and the other is responsible for replacing damaged or missing zooids. Without one of your clones, everyone in the RV would die, and RV would eventually stop moving. Same can be said about siphonophores and P. physalis.

The pneumatophore is the gas-filled bladder at the top; it’s the purple-bluish structure you can see floating on top of the water. This zooid is responsible for the colony’s movement. However, the gas-filled bladder works more like a sail; the wind and surface currents do the actual moving of the colony. This is how they got their name, because the gas-filled bladder resembled the sails of man-o-wars, a type of naval ship.

The tentacles are another organism, or zooid, of P. physalis. On average, the tentacles can extend 30 feet below water, but a single colony was recorded with tentacles as long as 165 feet! The tentacles contain venom-filled nematocysts, which they use to paralyze and capture prey. Portuguese man-o-wars feed on fish, shrimp, and other small creatures.

Gastrozooids are the polys in charge of digesting the prey and distributing the nutrients to the other polyps in the colony. Essentially, they are the digestive system of the colony. Unlike the sail and the tentacles, they have no distinctive “structure” on the colony, so they can’t be identified in a photograph.

The last type of zooid is responsible for reproduction. These polyps create other polyps for each of the groups, replacing those that have died or have been damaged. They are also responsible for exchanging genetic material with other Portuguese man-o-wars.

Portuguese man-o-wars are found in tropical and subtropical waters, and they can be found floating in large numbers—even in the thousands. I know in the US every summer, media warns the East Coast about these siphonophores washing up on public beaches.

P. phyaslis can be harmful to humans. I’d hate to be out swimming and get stung by the long tentacles! While live man-o-wars can be harmful to swimmers, dead ones are also a concern. While the venom is rarely fatal, it hurts worse than an army of wasp stings, and the nematocysts can still sting humans after death. So if you seem a dead one wash up on the beach—DON’T TOUCH IT!

If you notice Portuguese man-o-wars in the water or washed up, notify the lifeguards and everyone around you immediately. If you’ve been stung, do not use urine or vinegar on the inflamed area.

Dive manuals suggest that you carefully remove any remaining tentacles and flush the area with sea water, never fresh water. As soon as possible, immerse the affected area in hot water of at least 112°F for twenty minutes. This will denature the toxin and break up the chemicals.

I have never seen a Portuguese man-o-war in person despite living on the eastern coast of the United States and frequenting beaches in the summer. However, I don’t think I’m terribly upset with the idea, because with my luck, I’d get stung! Siphonophores are pretty interesting, though, and I can’t wait to share more with you!

Links and sources:
Reef Creature Identification Florida Caribbean Bahamas 3rd edition by Paul Humann, Ned DeLoach, and Les Wilk ⇐had the info on how to treat the sting
https://www.nationalgeographic.com/animals/invertebrates/p/portuguese-man-of-war/ ⇐in-depth look into the sections of the man-o-wars
https://oceanservice.noaa.gov/facts/portuguese-man-o-war.html ⇐simplified info

Blue Glaucus

Domain: Eukarya
Kingdom: Animalia
Phylum: Mullusca
Class: Gastropoda
Order: Nudibranchia
Family: Glaucidae
Genus: Glaucus
Species: Glaucus atlanticus

The other day, I got a strange text from my dad talking about an article that he found on the Internet describing a blue dragon that had washed up in Texas. He seemed really excited to show me the article because he thought I could blog about it. Well, “blue dragon” didn’t ring any bells, and I thought that it might have been an oarfish, which is dragon-esque. Instead, what I found is a nudibranch, most commonly known as a sea slug.

Glaucus atlanticus goes by many common names: blue glaucus, blue dragon, sea swallow, and blue sea slug, to name a few. No, it does not look like any slug you might have seen or land.

The creature has what looks like a head and a tail. Along its body are three pairs of fan-like appendages that look like wings. The blue sea slug can grow up to 1.2 inches (3cm) in length, which would make it the smallest dragon in the Guinness World Record book. However, it is not the smallest sea slug!

Most sea slugs live on the seafloor. They can live on coral, or the sandy substrate, or even rocky surfaces. Glaucus atlanticus isn’t like its cousins, though. Instead, they are a pelagic sea slug, meaning they live in the open water column. They have been sighted more often up towards the ocean’s surface.

The blue sea slug floats in the water column by storing an air bubble in its body, acting like an air bladder in fish. If it hangs out near the surface, how does it hide from sea birds?

Glaucus atlanticus has a special coloration that allows it to blend into its surroundings called countershading. The blue sea slug floats on its backside, showing the bright blue underbelly toward the sky. The blue helps it blend into the waves and makes it hard for sea birds to see the creature. On the other side, it is a grayish color that blends in with the surface water from below, making it nearly invisible to its underwater predators.

Countershading isn’t the only defense it has against predators. In fact, like most sea slugs, this is a creature you don’t want to touch—no matter how pretty it looks!

One of the things blue dragons consume is the Portuguese man o’ war, a type of hydrozoan known to give nasty stings to beach-goers. The Portuguese man o’ war has long tentacles, almost 30 feet long, which are full of stinging cells.

When the blue dragon consumes the Portuguese man o’ war it stores the hydrozoan’s stinging cells in those fan-like appendages. When a diver or predator gets too close, the blue dragon will brush up against the perceived threat and sting them with the stinging cells. It’s been reported that a sting from a Glaucus atlanticus hurts more than a sting from a Portuguese man o’ war—so watch out for these critters when swimming! They’re found in the warm waters of the Pacific, Indian, and Atlantic Oceans.

If anyone has any suggestions or requests, like this one, let me know! I want to write about what interests you.

Sources and links:
Reef Creature Identification: Florida, Caibbean, Bahamas 3rd edition by Paul Humann, Ned Deloach, and Les Wilk
https://scubadiverlife.com/marine-species-glaucus-atlanticus/ ⇐has dive-related news articles as well