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):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.
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: 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, and...fishing 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...
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: 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: 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: 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:
- pneumatophore (float)
- dactylozooids (tentacles for defense and prey capture)
- gastrozooids (feeding)
- gonozooids (reproduction)
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: 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: 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) 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...
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: 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.
Went to the beach last weekend, and got a few cute pictures: