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
https://www.britannica.com/animal/Portuguese-man-of-war

Mushroom Coral

Domain: Eukarya
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: Scleractinia
Family: Fungiidae
Genus: Fungia
Species: Fungia scruposa

Do you know what gets my attention? An old article about a species of coral that was documented eating jellyfish. But I’ll get to that later; first, I want to introduce you to Fungia scruposa, or the mushroom coral!

Found in the tropical waters of the Red Sea, Indian Ocean, and western Pacific Ocean, mushroom coral are unique for a few reasons. Unlike other hard corals, F. scruposa lives as a single individual instead of as a colony, much like the Atlantic mushroom coral of the family Mussidae. Don’t let their similar common names fool you, though. These two corals are not closely related to each other.

Juvenile mushroom coral start out as raised disks that attach to dead coral or rock. When they grow to about an inch in diameter, they detach themselves from their substrate. However, this does not mean that they’re super mobile. Instead, mushroom coral typically stay in the same area and inhabit the sediment or rubble.

But what happens if a strong wave comes through and turns them over? Fungia scruposa use their tentacles to right themselves when knocked over by waves or by another animal.

Mushroom coral get their name from their appearance. They have an irregular disk shape that is about 1 inch in diameter, sometimes a little larger. At the center of the disk is a raised mound with a deep-looking cut, which is the polyp’s mouth. The coral’s hard exoskeleton has several thin ridges that spread out from the center, making it look like the underside of some mushrooms.

Fun fact: did you know that the ridges on the undersides of mushrooms are called gills?

I’ve yet to see this coral while diving, but I absolutely cannot wait! Mushroom coral are unique for their class, because they live as solitary polyps and spend their adult lives not attached to anything. But on top of all that, they were also recorded eating whole jellyfish in the late 2000s—something that was completely unheard of!

There are some species of sea anemones—distant cousins to coral—that are known to eat jellyfish. However, these are the first hard corals that scientists have seen eating jellies. Unfortunately, the divers were only able to see the jellies disappear into the mouths of several mushroom coral, but they could never see how the mushroom coral captured the moon jellies. Still, it’s absolutely fascinating and may prove how resilient hard coral can be in a changing ocean environment.

And maybe you can be the researcher that discovers how they do it! Maybe you can discover more species of coral that will dine on jellyfish when the opportunity presents itself.

Sources and links:
Ocean The Definitive Visual Guide made by American Museum of Natural History
http://www.coralsoftheworld.org/species_factsheets/species_factsheet_summary/fungia-scruposa/
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8350000/8350972.stm ⇐an article about mushroom coral eating jellies
https://link.springer.com/article/10.1007/s00338-009-0507-7 ⇐another article about them eating jellies but with more detail

Sea Whip

Domain: Eukarya
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: Gorgonacae
Family: Gorgoniidae
Genus: Leptogorgia
Species: Leptogorgia virgulata

I’ve realized that so far the only corals I have mentioned have been hard corals—reef builders. I will admit, that I like more hard corals than soft, but that doesn’t mean soft corals aren’t worth talking about. Continuing with my Chesapeake Bay theme, I’m going to talk about a native soft coral, the Sea Whip.

Cue the 80s music: “Crack that whip!” “Just whip it!”

The major difference between hard and soft corals is the composition of their bodies. Hard corals have permanent, rigid exoskeletons that house the coral polyps. These structures require large amounts of energy to build, which is why it can take a year for hard corals to grow just an inch, at best. Soft corals, however, lack that rigid calcium carbonate skeleton. Instead, soft corals are mostly made of living tissue that allows the soft corals to assume more creative shapes.

Sea whips, Leptogorgia virgulata, have long, thin branches that can grow up to a meter long. Their coloring can vary from red, to tan or orange, to purple. The polyps are always white, so sea whips look like they’re covered in white fuzz. Most soft corals are more colorful than their harder cousins.

Sea whips are found in reef environments and can tolerate low levels of salinity, so they are most common in nearshore areas that are more influenced by the tide. They range from New York to the Chesapeake Bay and from Florida to Brazil. In the Chesapeake Bay they thrive in the salty waters of the lower section of the bay.

L. virgulata are suspension feeders, so the polyps use their long tentacles to snag plankton and other tiny particles that are suspended in the water. When sea whips are born, the tiny polyps are carried by waves and currents. When they reach adulthood, so to speak, they become sessile meaning they cannot move from the hard substrate they land on. So they rely heavily on water circulation to stir up the water and bring in more plankton and nutrients for them to feed on.

I have yet to see a sea whip while diving, which is something I wish to change. But I wanted to share this soft coral to show that not all corals are found in tropical places, and that corals can be a lot more diverse than we think. And I’m happy to report that as of this writing, the populations of sea whips in the Chesapeake Bay and other monitored areas are considered stable!

Sources and more info:
https://www.chesapeakebay.net/discover/field-guide/entry/whip_coral
http://www.dnr.sc.gov/marine/sertc/octocoral%20guide/Leptogorgia_virgulata.htm
https://naturalhistory2.si.edu/smsfp/IRLSpec/Leptog_virgul.htm

Atlantic Mushroom Coral

Domain: Eukarya
Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Order: Scleractinia
Family: Mussidae
Genus: Scolymia
Species: Scolymia lacera

Not all hard coral grow to be great big structures. And while most coral are considered to be a colony of polyps—i.e., individuals living together—there are some that are quite solitary. Some of them, like the cup corals, live a bit differently than their cousins and distant relatives.

Atlantic Mushroom coral, or Scolymia lacera, is one of a few cup corals found in the Western Atlantic Ocean. In fact, they occasionally can be found in deep-reef environments and on reef walls in the waters around Florida, the Bahamas, and the Caribbean. They prefer well-lit areas on rocky surfaces and outcroppings, somewhere nice and stable with enough light to help out their zooxanthellae friends.

S. lacera varies in color from shades of light gray to green, blue-green, and brown. The few that I have seen while diving were a mix of blues and greens, almost like an alternating stripped pattern—though this isn’t the same of all individuals.

Unlike other coral, the whole structure that is S. lacera is made up of a single polyp. That’s right; this species of coral is not a colony like its other hard coral cousins. Instead, it is a single large, fleshy, roundish polyp that looks a bit rough around the edges—texture-wise, that is. The whole structure that you see is the corallite, or the skeletal cup in which an individual polyp sits in and can retract into. For S. lacera, the center of the corallite can be either flat or curved inward; rarely is it seen with a raised center.

The Atlantic Mushroom coral can grow to between 2.5 and 6 inches and is the only type of cup coral that you can identify in person if it’s larger than 4 inches in diameter. Any specimen smaller than 4 inches has to have its corallite structure examined for identification.

During the night and in turbid, cloudy conditions, the polys will extend their tentacles in the hopes of grabbing food.

I think these guys are really cool because they break the mold, so to speak, when it comes to most hard corals. Instead of being a colony of individuals, each structure is a single large individual. They’re also pretty neat to spot on the reefs because they can be these bright colorful spots amongst drab shades. When I first saw them I didn’t think they were coral. It wasn’t until I started taking classes and we discussed them that I learned what they were.

Sources:
Reef Coral Identification: Florida, Caribbean, Bahamas 3rd edition Paul Humann and Ned DeLoach

https://coralpedia.bio.warwick.ac.uk/en/corals/scolymia_lacera <–At the time of posting this article, I hadn’t gotten the rights to share any photos of the coral, but you can see pictures of this species at the link–please take a look!

Coral part 2

Photo taken by Dr. Alexander Mustard. You can find more of his amazing photos on his website www.amustard.com

Last time, I mentioned all the factors that determine a coral’s success in an area, and most of those factors relate to hard coral or reef building coral. Soft coral are a bit different from their constructive cousins; for instance, they don’t all rely on zooxanthellae, and so most of this information pertains to hard corals—but don’t worry, I’ll get to soft corals eventually!

For hard coral, the factors that affect their success in an area include water temperature, salinity, depth, water circulation, and clarity.

Most of these factors aren’t hard to explain because we can relate to them. For instance, we don’t like to be too warm or too cold. It’s the same with coral: they don’t like their water to be too warm or too cold, so their ideal range is between 85°F‒70°F. This is not a very strict range because there are reefs and species found outside these temperatures, but for the most part this is important for reef-building coral.

Hard corals also don’t like their water to be too fresh or too salty. They prefer their water to have a salinity level between 30 and 40 parts per thousand (ppt).

Next, we’ll talk about water circulation. This one is really important because coral can’t move elsewhere once the food is gone, they’re sedentary. They’re not like humans, who can get off the couch and grab food when they’re hungry. Coral pretty much have to be in an area that always has food—so it’s like if your cousin decided to live in the supermarket for the rest of their life. Coral feed on zooplankton, which for now let’s describe as plankton-size animals, and that means that the coral’s food isn’t regularly replenishing. Instead, coral rely on water circulation, either through water currents or wave actions, to stir up the water and bring nutrients and food to them. Without good circulation, coral can easily starve, even the hard coral that obtain most of their energy from zooxanthellae.

The final two factors determining coral survivability are especially important to hard coral because of their partnership with zooxanthellae, and these factors are related to sunlight: water clarity and depth. Water clarity is defined by how clear the water is. If the water is really cloudy and full of particles, then the zooxanthellae may not be able to receive enough light for photosynthesis. Depth has similar effects: sunlight can only penetrate so far into the ocean before the only visible light comes from bioluminescent creatures. If the coral is anchored too far from the surface, then the zooxanthellae may not get enough light and the pair can die.

There are coral that can survive outside of these factors; for instance, they have discovered coral in the deep ocean at depths of 6,000 m (20,000 ft)—that’s almost four miles below the ocean’s surface. Deep-sea coral are fascinating because they vary from their shallow-water relatives, but I’ll get to those later.

If the hard coral’s habitat changes beyond these set factors, then it can have devastating impacts on the organism. If the conditions don’t return to the normal, then the coral will expel their zooxanthellae in a process called Coral Bleaching. Some research has suggested that the coral can reacquire their zooxanthellae or even acquire new zooxanthellae. However, there are still a lot of unknowns in regards to Coral Bleaching and coral health, which is why continued research is so important!

If the coral die then the reef dies, and from there it’s a domino effect that will very quickly impacts us. Without the reefs the world fish populations will dramatically decrease. Less fish means less food for the animals that live in the ocean, and less fish for us as well. If we compete with creatures like dolphins and whales for food, then those populations of animals will dramatically decrease as well. All in all, coral reefs are the rainforests of the sea in terms of biodiversity, habitat, and oxygen production.

It’s not all desolate and hopeless. There is research being done through the field of aquaculture in trying to grow coral ourselves to help save the reefs, most of which are being done at aquariums and universities. Researchers are trying to figure out ways to preserve the reefs that we have now, and to protect them from further climate-change-inflicted damage.

However, a grim-looking future faces us if we can’t curb the effects of climate change on our oceans, and that’s why YOU are so important in this struggle too. Everything you can do, big or small, to saving energy and reducing plastic use to conservation research programs will help lessen the impact of climate change and preserve our reefs for future generations.

Golden Jellyfish

Photo of a Golden Jellyfish taken by Dr. Alexander Mustard. More of his photos can be found at http://www.amustard.com

Domain: Eurkaryota
Kingdom: Animalia
Phylum: Cnidaria
Class: Scyphozoa
Order: Rhizostomeae
Family: Mastigiidae
Genius: Mastigias
Species: papua etpisoni

Last time, we talked about Jellyfish Lake in the Palau region of the Caroline Islands archipelago. We learned that the meromictic lake, which has distinct layers of water that do not intermix, is the only place you can find Golden Jellyfish.

I highly recommend putting this place on your bucket list, not only would you get killer pictures but you’ll experience something unlike anywhere else in the world! Now, let’s move on to the special guest of the day.

Golden Jellyfish (Mastigias papua etpisoni) are a species of jellyfish that are closely related to the spotted jellyfish that can be found in the lagoons near Jellyfish Lake. Like coral, they benefit from a close relationship with zooxanthellae. What, did you think coral were the only ones to be best friends with the greatest algae of the ocean?

Like coral, the jellyfish house the zooxanthellae in their tissue which gives the jellyfish their golden color. They also have a mutualistic relationship with the algae; the golden jellies provide housing, waste that the algae uses for nutrients, and sunlight in exchange for the sugar that the zooxanthellae don’t use from photosynthesis.

In fact, it’s the sugar that gives the jellies all the energy they need to grow and reproduce, because they don’t gather food on their own since they lost their ability to sting prey through untold years of evolution. It also allows them to propel and migrate through the water, giving the zooxanthellae access to sunlight throughout the day as the sun moves across the sky, casting shadows on the lake.

This migration has a positive effect on the lake’s ecosystem, by stirring up the nutrients and microorganisms found in the water, providing one of the only sources of circulation in the layers they inhabit. So in this scenario everyone wins: the zooxanthellae get everything they need to make food, the jellies get all the leftovers, and the surface of the lake gets stirred up for the other organisms that call it home.

But the jellies aren’t without predators. They’re preyed upon by anemones that concentrate in areas that the jellies frequently migrate through, creating a bottleneck effect. Thankfully, the sheer number of Golden Jellyfish provide their predators a healthy diet without affecting the population too much.

I find these guys to be really cool creatures to study just because of their relationship with the zooxanthellae and their ecosystem. In general, the whole lake is fascinating and worth the time to read about. It’s a wonderful example of how crazy nature can become when isolated from what used to be similar environments and/or species.

Sources and cool links to check out:
https://palaudiveadventures.com/palau-jellyfish-lake/#Golden
https://www.nationalgeographic.com/animals/invertebrates/g/golden-jellyfish/