Summer Time Is Beach time

Even though the summer sun can be quite hot here in Boca, in one respect we don't have it nearly so bad as people who live farther north. Our maximum temperature is usually quite a bit cooler than the maximum in places like Washington, D.C. or New York. We may get warm sooner, and stay warm longer, but for us a killer heat wave is the mid-90s. As Henry, Portier, and Coyne describe it, the average annual maximum temperature in southern Florida is 5° less than "most areas east of the Mississippi River and south of the Great Lakes" (7). That said, June was an extremely hot month. And July hasn't started off much cooler. So we've gotten in the habit of going to the beach early in the morning (by early I mean the crack of nine,  not the dawn patrols of my misspent youth) on the weekends. That gives us plenty of time to enjoy the beach before the madding crowds arrive. Eric loves the water, particularly when it's as calm as it was last weekend. Glassy water, bright but not yet punishing sun: a recipe for fun! This weekend, though, the winds were out of the east, and the ocean was quite a bit rougher. We still had fun, but the waves even in the shallows were stronger, and we didn't last nearly as long. One of the last waves rolled us over and we got a dunking that took a bit of the fun away. Home time! Mommy and Daddy got a good bird sighting out of the rough conditions, though: a Magnificent Frigatebird, fairly uncommon in Palm Beach County (image from Wikipedia, as I rarely take my camera to the sand and salt of the beach):

Female frigatebird (Wikipedia)

Our bird was traveling incognito, though, with neither white on the throat (female field mark) nor red throat sac (male field mark) visible. I assume this means it was a male with its throat sac hidden, because females and juveniles always display the white. It was definitely a frigatebird, though; there's no mistaking that wing shape or the piratical air, or the ease with which it plies its trade in the breezes over the beach. It owes this last trait to the fact that it has "the greatest ratio of wing surface area to body weight of all living birds. This fact, together with the bird's very long, deeply forked tail, makes the frigatebird aerodynamically unrivaled for soaring and maneuvering" (51). (I would say that the Swallow-tailed Kite puts on a pretty good show, but for all its grace it is noticeably "heavier" on the wind than the man-o-war bird.) Stevenson and Anderson's map shows only spring and winter sightings from Palm Beach County; nevertheless, I've seen them often enough in summer that I'm not in any rush to report this sighting. (Our Palm Beach County Checklist of Birds lists them as unusual in spring, fall, and winter, and Rare (even rarer than unusual) in summer). References Henry J.A., Portier K.M., & Coyne, J. 1994. The Climate and Weather of Florida. Sarasota: Pineapple Press. Hope, B. 2003. Palm Beach County Checklist of Birds. Audubon Society of the Everglades. Stevenson, H.M., & Anderson, B.H . 1994. The Birdlife of Florida. Gainesville: UP of Florida.

Marine invertebrates, part two

Jellyfish and hydrozoans are only one type of animal that gets washed up on the beach during our easterlies. During our explorations last weekend Marcella ran across a colony of goose barnacles that had washed up as well: They're attached to an orange substrate that reminds me of a sponge, but I know next to nothing about poriferans, so I can't get much further with that (I had thought it was an agglomeration of red sponge, Haliclona rubens, but the color is wrong and they're usually more fingerlike than clumpy). But there are other, more readily identifiable organisms attached to them: Goose barnacles (Lepas anserifera). These are harmless animals that resemble mollusks (the shells sure look a bivalve shell, don't they?), but that are in fact arthropods: sessile crustaceans, to be somewhat precise. You can see their jointed legs (arthro-pod) poking out of their shells; they use them to gather food from the water: Sorry for the blurriness of the pix; I have to remember to bring a real camera on these excursions. The cellphone camera just doesn't cut it, although it does allow for pix where I would have had no pix at all were it not for it, so... "It's a poor workman who complains of his tools." Grumble gripe mumble mumble. Lepas, according to Langstroth and Langstroth (why do the best beach and ocean guides seem to be written by husband and wife teams?), are pelagic species. They settle "on floating objects such as logs, bottles, ships, floats" and go about making a living with their feathery thoracic legs, which "rhythmically gather in suspended food particles and may enhance respiration by creating water currents around the body. Lepas feeds on midsized planktonic organisms; in the laboratory it will even take animals larger than itself." When we flipped the whole assembly over, we noticed that there was a worm of some sort as well. It looks like a polychaete worm, but with over 9000 species worldwide, and only a few photos in any of my guides, I can't even begin to think what it might be... So there you have it: one animal of three identified for you. Just goes to show how much there is to know out there...

Marine invertebrates, part one

Springtime in south Florida generally means onshore breezes around the clock on the Atlantic coast. These steady breezes tend to push ashore large numbers of Physalia physalis, known as the Portuguese man o' war, as was the case last weekend at Red Reef Park in Boca Raton: According to my Witherington guide (Florida's Living Beaches), April and May are the peak months for both size and abundance of these washed-up siphonophores. Even though it's not a true jellyfish, the fact that both this animal and the true jellyfish can deliver a painful sting makes the distinction irrelevant in most people's minds. After all, it's easier to call something that looks like a jellyfish, floats like a jellyfish, and stings "like a jellyfish," well, a jellyfish! The fact that it doesn't really look like a jellyfish if you look closely enough doesn't really matter to most people; the fact that it floats on top of the water with an inflated gas bag, instead of swimming or floating freely in the water column like a jellyfish doesn't really matter to most people; the fact that its sting is many times more venomous than that of most jellies doesn't really matter to most people, either. The sting alone is enough to discourage most people from looking at it closely enough to notice the other differences between it and the true jellyfish. In fact, the sting is what gives the entire phylum, Cnidaria, which includes such diverse animals as corals, anemones, true jellyfish, and hydrozoans, its name. It derives from the Greek knidē, nettle. The phylum consists of radially symmetric animals that possess specialized stinging cells called nematocysts:
If collar cells and spicules are defining characteristics of the Phylum Porifera, then nematocysts define cnidarians. These tiny organelles, [like] . . . cocked guns, are both highly efficient devices for capturing prey and extremely effective deterrents to predators. Each contains a coiled, tubular thread, which may bear barbs and which is often poisoned. A nematocyst discharges when a prey species or predator comes into contact with it, driving its threads with barb and poison into the flesh of the victim by means of a rapid increase in hydrostatic pressure. Hundreds or thousands of nematocysts may line the tentacles or surface of the cnidarian. They are capable even of penetrating human skin, sometimes producing a painful wound or in extreme cases, death. (From ADW entry)
So if the sting defines the entire phylum, it's not too surprising that few people bother to make the distinction between the true jellyfish and the distantly related siphonophores. Take a look at the pictures below and see if you can tell which one is a "true" jelly: Did you get it right? All three are coelenterates (another word for cnidarians), but only the last is a "true" jelly, one of the moon jellies seen in a hasty snapshot from a pelagic birding trip I took in California last fall. Note how the jellyfish swims under the surface of the water, instead of floating on top, pushed by wind and wave action. Harder to tell at a glance, but true as well, is the fact that this is a unitary animal, rather than a colonial "superorganism." The first two, the Portuguese man o' war and the By-the-wind sailor are colonial hydrozoans, "individual" animals composed of several different types of unisexual or asexual polyps and free-swimming sexual medusae. Both of them come in left- and right-sided versions as well. That is, the sail-like structure at the top of the pneumatophore (the gas bag) is angled either to the left or to the right. Thus, a left-sided and a right-sided animal would travel at right angles to each other if pushed by the same breeze. (This means that most mass strandings involve only one or the other body plan; it would be hard for a group of opposite-sided animals to stay together.) Velella velella, the By-the-wind sailor, is placed by some in the order Athecata, which means "without a theca" (a theca is an enveloping sheath or case, from the Greek thēkē, case). Because athecata is not a monophyletic order, it will most likely change as more becomes known about these organisms. Other taxonomists place V. velella in the now-obsolete order Chondrophora (Greek chondros, grain or cartilage), or the current family (a higher taxonomic unit) Porpitidae. Below is a picture of a by-the-wind sailor that's been washed up long enough to have lost its blue coloration: Physalia physalis, the Portuguese man o' war, is in the order Siphonophora, although it is by no means representative of that order. As far as I know, Physalia is the only genus in the order that floats on the surface of the water, rather than in the water column. There are some amazing creatures in this order that have only recently become better known to science. I can't do much better than to quote to the aforelinked Casey Dunn:
Siphonophores challenge us to think about what we mean when we call something an individual, a concept that we usually think of as being quite straightforward. Is a single zooid or an entire colony the siphonophore “individual”? The answer is that you have to specify what features you are interested in before you can expect a meaningful answer. Do you mean ecologically? The entire colony functions as a single organism whether it is predator or prey. So the colony is an ecological individual. The same can be said for behavior. How about evolutionarily? There are two different components to this question. If we ask how evolution acts on siphonophores now, they are individuals. All the parts of the colony are genetically identical and the colony lives or dies as a whole (except for the eudoxids described later). So siphonophores are evolutionary individuals with respect to how natural selection shapes them today. The other way to look at evolutionary individuals is by descent. We can do this by taking a look at two animals and asking which structures descend from the same feature of a common ancestor. Just as this leads us to recognize that bat wings are modified arms, it shows that siphonophore zooids are polyps and medusae, structures that can be free living animals in other species. So this argument leads to the conclusion that the zooids of siphonophores are individuals. This is not contradictory to our previous conclusions, we are just looking at a different feature of individuality.
In the case of the man o'war, each colony consists of four distinct polyps, each of which has a special function:
  1. pneumatophore (float)
  2. dactylozooids (tentacles for defense and prey capture)
  3. gastrozooids (feeding)
  4. gonozooids (reproduction)
Without all four types, this colonial "superorganism" (with apologies to Wilson and Hölldobbler) would not function. Below is a picture of several men o' war that wound up dying in the same bed of sargassum: Whether you consider each colony as an individual or a plurality, there are at least three of them in that photo. The by-the-wind sailor is also a colonial animal, rather than a single individual like the jellyfish, but its composition is slightly less famous than its larger cousin, and I'm nearing 2000 words, which makes this blog posting Too Long Already. I'm belaboring the distinction between these hydrozoans and the other coelenterates because it's not just an abstraction. It's grounded in real, physical differences between the two groups. If we limit ourselves to a simple experience (ouch! they both sting! they must both be jellyfish!), or a cursory glance (they all look like gelatinous blobs) we run the risk of building our mental worlds on false grounds. These animals (don't) swim like jellyfish, (don't) look like jellyfish, and (do) sting like jellyfish; they are really not jellyfish at all. Perhaps this tendency to give cnidarians short shrift stems from our landlocked perspective, colored by our evolutionary past. Our distant ancestors left the oceans a long time ago, but even before that, at least as far back as we can reliably speculate, they were unitary beings arranged on a bilaterally symmetric body plan that centered around a spinal column, or notochord (that longitudinal flexible rod of cells that forms the supporting axis of our body). However, only a very few of the organisms on this planet have one. Possessing a backbone is such a distinguishing characteristic that this one character defines the phylum Chordata within the animal kingdom. But there are many, many other phyla within the kingdom Animalia: "the" inverterbrates, as we call them, as if the fact that they don't have a backbone somehow is sufficient to characterize them in binary opposition to our own group, the vertebrates. Remember, though, the absence of a character is not a defining characteristic of any taxon, so to lump all animals without a backbone into one category defies logic. (Think: "Man is the animal without wings.") However, since we are the ones defining the taxa, and we have backbones, it's hard not to put "like-us" into one category, and "not-like-us" into another. Doing so, though, creates a hugely disproportionate grouping because, depending on your favorite taxonomy, invertebrates comprise anywhere from 13 of 14 (Wikianswers), up to 36 of 37 (Margulis & Chapman) of the phyla in the kingdom Animalia. (And if you're a phylogenist or cladist, you don't even bother with these considerations, you just add grouping after grouping. This one from the Tree of Life web project seems pretty accurate.) And all of these phyla are arranged along a stunning variety of alternate body plans. The cnidarians, or coelenterates, are one of those phyla that tax our interpretive powers to the utmost. For years we didn't even know the body plan of many of them because their bodies are so fragile they exploded in our nets, or even just at the approach of the lights of a submersible! Our perspective as terrestrial animals that only occasionally venture into nearshore marine environments has really slowed our understanding of this group of animals, except for those few that are hardy enough to exist at or near the surface. Someday, after I get an underwater camera rig, I might delve more deeply into those other colonial cnidarians, the corals, with their symbiotic relationships with algae called zooxanthellae. But sea level rise and rising ocean temperatures might drive these fragile ecosystems to extinction before I can get around to buying a waterproof digicam and time to learn how to dive. So for now, I'll concentrate on those organisms that I can find in the tidal wrack after a strong easterly blow like we've had for the past week or so. More on what I found later... References Dunn, C. "Siphonophores" (On-line), Siphonores. Accessed April 12, 2010 at Hammond, G. 2009. "Hydrozoa" (On-line), Animal Diversity Web. Accessed April 12, 2010 at Myers, P. 2001. "Cnidaria" (On-line), Animal Diversity Web. Accessed April 12, 2010 at Tree of Life Web Project. 2002. Animals. Metazoa. Version 01 January 2002 (temporary). Accessed April 13, 2010 at in The Tree of Life Web Project, Witherington, B. and Witherington D. 2007. Florida's Living Beaches: A Guide for the Curious Beachcomber. Sarasota, FL: Pineapple Press.

Florida word of the day: psammophyte

Psammophyte. This seems to be a fancy way of saying seaweed. Since this word is too hifalutin' for the American Heritage or even Merriam-Webster teams to take on, here's a definition of the term from Dawes and Mathieson (Seaweeds of Florida, U of Florida P 2008):
A plant that grows in unconsolidated sediments or on rocky subtrata that is impacted by sand scouring; these plants show specialized morphological and/or reproductive adaptations.
"Unconsolidated sediments" sounds to me like sand; not sure what else it could be (gravel or crushed shells, I suppose). And since psammo is Greek for sand, I'm going to say that it's sand. As far as seaweeds go, there are apparently all kinds of ways of classifying them. One is the various types of "attached macroalgae": Psammophytic and lithophytic (lithos is rock) appear to be the binary categories here. The opposite of attached macroalgae would presumably be planktonic. As Dawes says, "most seaweeds are lithophytes that grow attached to hard substrata and form some of the most productive communities in the world" (17). So what seaweeds are psammophytic? Well, to answer that question, I'd have to go back to the library, request an interlibrary loan, and reobtain my copy of Dawes and Mathieson. That sounds like a lot of work. What about a Google search? Turns out that you don't have to be a marine plant or algal growth to be a psammophyte. Any of those plants you see on sandy soil can be called psammophytic. So dune plants, like these lovely sea oats, would qualify:

Sea oats (Uniola paniculata)

Turns out it's hard to see the sandy substrate in the shot above, so here's a shot of a neighboring plant even closer to the water than that:

Beachstar (Cyperus pedunculatus)

And, just in case you need some color with your sand-loving plants, here's a beautiful, and endangered, psammophyte of south Florida: Beach Peanut (Okenia hypogaea)

Beach peanut (Okenia hypogaea)

I saw all three of these psammophytes on a field trip with the Florida Master Naturalist program back in 2008. But I hadn't known the hard word that describes them all until I ran across it in research on the seaweeds of Florida. Now I have a fairly long agenda of photos to take when I get to the beach again...

Boca Beaches

One of the things that I admire about Boca is that, despite its many faults, it does have some semblance of a commitment to environmental practices. For instance, it isn't supposed to groom the beach above high tide during turtle nesting season. So the beach gets a little ugly, but it keeps those gigantic machines off the turtle nests. Well, apparently no one told the operator of the giant beach groomer that we saw a few weeks back, chugging south along the beach well above the tide line. You can see how neat the beach above high tide looks in the picture below: Thing is, this crawler was not limiting itself to the tide line. Unfortunately, I didn't get any pictures of its path (it wasn't something I was thinking of as I was concentrating on taking pictures of the boy and his lovely mother), but trust me: the adherence to this regulation is mighty loose... It did manage to swerve around the marked turtle nests, but what if (heaven forbid!) the volunteer turtle nest spotters missed a nest? See below for a few shots of the nests and the metal mesh that is supposed to protect them from raccoon predation before hatching (nothing can protect a newly hatched turtle, or tern for that matter. I've heard heartbreaking stories of crows waiting outside tern exclosures for the hatchlings to emerge, and gobbling them down one by one as they do). Note how deliciously untidy the beach is around them, with bits of seaweed everywhere. That's what a beach is supposed to look like! Not being a turtle expert, I'm not sure what kind of turtles are involved in these nests, but the most common turtle along our shores is the loggerhead, followed by green, then leatherback. If you had the hi-res photos, you could zoom in and see a CC on most of the signs. I assume that's shorthand for Caretta caretta, the loggerhead turtle. The numbers would be the number of eggs in the nest, and the date, well, I would hope that's self-explanatory: the date the nest was laid. So most of the nests I've seen have been loggerhead nests until I hear different from the people who conduct the research on the turtles of Boca. The studies are conducted by the Gumbo Limbo Nature Center, in conjunction with Florida Atlantic University. The best books on sea turtles are still Archie Carr's, particularly The Windward Road. The recent title by James Spotila updates Carr, but can't match his prose. For an epic look at the leatherback, there's the recent account by Carl Safina, Voyage of the Turtle.