Food chains link the creatures of coastal ecology

Don’t stick your hand in that shell! You don’t know who might be home. It could be a carnivorous snail or a “clawsome” crab. Take a look at our Texas state shell, the lightning whelk or left-handed whelk, which feeds on bivalves like oysters and clams. Perhaps the snail that makes the shell is still hiding inside, or perhaps the shell is home to a hermit crab. Unlike most crabs, hermit crabs use the shells of snails as homes to protect their soft bodies.

Hermit Crab

Hermit crab taking residence in an empty lightning whelk shell.

Texas is home to some fascinating creatures, and our coast is no exception. In addition to the Gulf side beaches, there are salt marshes, jetties and the bay to investigate. Our coastal habitats are just waiting to be explored, and with the right gear, you can see organisms at every trophic level. (You knew I was going to talk about food chains, didn’t you?) 

OLYMPUS DIGITAL CAMERA

Lightning whelk snail retracted into its shell, operculum blocking the opening.

Most folks will notice some of the upper-level consumers: birds like pelicans and gulls. Who could miss the gull snatching your unattended hotdogs? Or the pelicans plummeting into the water face first to catch fish? Maybe you’ve noticed fishermen along the beach as they pull in small bonnethead sharks. Some animals may require good timing and tons of mosquito repellent to see, like our rare and critically endangered Kemp’s ridley sea turtle. If you pay attention, there are even rattlesnakes catching mice that are feeding on insects and plants in the dunes!Food Web

As you follow a food pyramid from the apex down to the base, top predators like humans and sharks feed on the organisms in the level below. There you might find the larger bony fish we feed on, like redfish or snapper, and below them you can find some of the crustaceans and mollusks they feed on in turn. Crustaceans, like our blue crabs, stone crabs, and the smaller ghost crabs, often scavenge in addition to feeding on mollusks, worms, or even plant matter. Many of our mollusks are filter feeders, like oysters, pulling algae and plankton from the water. Finally, at the base of the food pyramid, there are the producers. The phytoplankton and algae make their own food with energy from the sun.

A food chain pyramid is a great way to show different types of food chains on one example. I used a pyramid created by my friend Julia and drew examples of food chains from our coast on it. One side has the trophic levels on it and the other three sides have example food chains. What’s on the bottom of the pyramid? The Sun, of course!Pyramid

Coastal ecology isn’t just about sand, shells, and dodging gulls. It’s also about the interactions between plants, animals, and their environment. The plants anchor the dunes, the dunes protect and replenish the beach sand, the sand houses animals like mole crabs and mantis shrimp, and we get to enjoy it when we protect it.

If tracking home beach sand in your shoes, car, towels, and suits doesn’t excite you, our new Hamman Hall of Coastal Ecology may be just the air-conditioned trip to the coast you need on a scorching summer day in Texas. Members, come join us Memorial Day weekend to see wonders of the Texas coastline!

Beach Bugs!

I recently returned from a wonderful trip to Galveston. It was so relaxing, sitting on the beach, listening to the waves and watching the birds. The beach is such a peaceful place and Galveston is very close to my heart because my husband and I got married there! Although I escaped with nothing but a few mosquito bites (my husband was not as lucky!), I got to thinking about bugs at the beach and the horror stories I have heard. I’ve heard about sand flies, sand fleas, sea lice; all kinds of crazy stuff. I decided to do a little research to see what was true and what was nothing but beach bug lore. I was absolutely shocked at some of the things I read, especially when Googling “sand fleas”! Most of the things I found were contradictory, inaccurate, and just plain ridiculous! The biggest problem seems to be the confusion between all of the common names. People in different parts of the world may refer to the same organism as several different things. That’s why scientists use Latin scientific names that are consistent across the world. So, here it is, the skinny on some of those beach pests we all hear about, what you should worry about, and what is no big deal!

Sea Lice

she don't use jelly
Creative Commons License photo credit: brainware3000

Well here’s a misnomer for you! I’ve never even heard of sea lice, but one of my co-workers mentioned them while I was researching. Many of you may have heard of them because apparently they can be quite a problem! It’s a misnomer because the real sea lice are tiny crustaceans that live in the ocean and feed on certain types of fish, but don’t bother humans at all. What we call sea lice are actually larvae of jellyfish that float around in clouds in the ocean. Although they are tiny, they still possess those nasty stinging cells or nematocysts. If you’re swimming in the ocean, they can become trapped between your bathing suit and skin. This is when you can be stung. The stings cause intense itching and burning which result in a rash with small raised blisters.  The rash can last anywhere from two days to two weeks, but most of the time they go away with no medical attention necessary, just lots of cortisone cream and Benadryl! Sea lice are common along the gulf coast, the Caribbean islands, Mexico and South America. Most beaches have warnings if the waters are heavily infested. The season for these pesky baby jellyfish usually runs from April through August.

Sand Fleas

It took me forever to get to the bottom of this one. I asked people I knew if they’d ever been bothered by what are known as “sand fleas”. The general consensus was, no. I read some of the most ridiculous things, however. I read that they attack your feet and burrow into your skin. I read that they attack fish and kill them. I read that they are crustaceans with wings, that feed on seaweed and also suck blood, but only from your feet. What?!?! So, this is what they really are. The common sand flea (Orchestia agilis) is an amphipod, or a small, terrestrial, shrimp-like crustacean. They burrow into the sand and they feed on decaying plant and animal matter that washes up on the shore, especially seaweed. They do not want anything to do with people. They obviously are not fleas, not even insects. However, they jump, similar to the way fleas do and they live in the sand, so hence the name sand flea. They are found all along the Atlantic coast, so you’ve probably seen them before. There is a more malicious animal that sometimes goes by the name sand flea, but more often is referred to as the chigoe flea. Tunga penetrans is actually a type of flea, but they are not like the more common cat flea that bites our domesticated pets. They are the smallest known species of flea. The chigoe flea lives in soil and in sand. They feed on the feet of warm blooded hosts such as humans, dogs, cattle, sheep and mice. When the female is ready to reproduce, she will burrow into the skin of the host, which is where she stays until after she releases her eggs, in about two weeks. After this, she dies and is sloughed off with the skin of the host. They can jump no higher than 20 centimeters, so they usually burrow into the foot or ankle. So, this is a little creepy, but don’t worry, they’re only native to the tropics, such as Central and South America.

Sand Flies

Female horse fly
Horsefly
Creative Commons License photo credit: Radu P

This is a pretty general term that can really refer to any biting fly you would encounter at the beach, besides a mosquito. This could even be a type of horsefly that is associated with that type of habitat. Most commonly, the name sandfly refers to flies in the family Ceratopogonidae. These are small biting midges, only 1-4 millimeters in length that live in aquatic habitats all over the world. Like mosquitoes, it is only the female that sucks blood to get protein in preparation for laying her eggs. The bite itself is too small to feel. It’s not until later when your skin starts to react with the proteins in their saliva that you start to feel the itch.  Because they go unnoticed, they can bite you a lot, that’s why they are such a pest! Bug spray is sufficient protection against these flies, but I never wear bug spray and haven’t been bothered by them, so I don’t think they’re much of a problem around us.

Salt marsh mosquitoes

I’m sure almost everyone has run to the car to get away from these vicious mosquitoes and their painful bites! Aedes taeniorhynchus and Aedes sollicitans are two common species found along the Texas coast. They lay their eggs in brackish and saltwater pools left over from the tides. There is no mystery about these ladies. They’re big, they’re hungry and they will come after you any time of the day whether you’re swatting at them or not. They are larger than many freshwater mosquitoes so they’re bites actually sting a bit. In other parts of the world, they are vectors of Venezuelan and Eastern Equine Encephalitis. Luckily, in our area, this is not a problem, but they are a prime vector of dog heartworm, so if you live near the beach, keep your dogs on a heartworm preventative.

I certainly had my fair share of them at the beach, which is what got me thinking about other parasites that may be lurking at some of our favorite vacation destinations. My conclusion: wear bug spray and heed any warnings at the beach and you should be in tip-top shape. You’ll hopefully leave with nothing worse than a minor sunburn and relatively few mosquito bites! Until next time, happy bug watching!

The Formation and Preservation of the Solnhofen Fossils

Our new Archaeopteryx exhibition has stunning complete fossils of fish, turtles, crocodiles, shrimp, sharks and much more, all from Solnhofen, Germany. In this blog, Dr. Bakker explains why Solnhofen produced and preserved so many spectacular, intact specimens.

The Mystery of Tropical Germany

From the first diggings in the late 1700’s,  Solnhofen presented a profound puzzle: Why was  Germany tropical in the Jurassic?

The fossil evidence was perplexing:

Fish
Amiopsis Lepidota

Big, long-lived reefs grow only in the tropics – how could northern Europe have supported the Solnhofen reef?

Large crocodiles thrive only in the warmest climate – how could giant sea-crocodiles flourish at Solnhofen?

Huge tree ferns today are emphatically warmth-loving plants – how could tropical ferns grow luxuriously at Solnhofen?

The mystery was world-wide. In the Jurassic, big crocodilians, tree ferns and reefs had spread all over Europe, Asia and North America. The tropical belt must have extended into Alaska and far south into Argentina.

Solnhofen was part of the proof that the Jurassic was one of the warmest periods in the history of life. Since the end of the Jurassic, on average Europe and North America suffered a gradual decrease in winter warmth.

Solnhofen – A Real Jurassic Park

Big-Budget movies have made the Jurassic Period  the most famous sector of geological time in our modern world. But in fact, the Jurassic was already world-renowned by the 1830’s. The first carnivorous dinosaurs known from good skeletons came from the Jurassic of Oxford. The first dinosaur tracks discovered in abundance were from the Jurassic of Massachusetts. The first complete skeletons of giant sea-reptiles were excavated from the Jurassic of southern England.

But no locale has gave finer fossils from the Jurassic than Solnhofen, Germany. Beginning in the mid 1700’s, Solnhofen has provided a never-ending stream of petrified animals and plants.

Fish
Liodesmus Sprattiformis

The exquisite skeletons lie in lithographic limestone, a rock that records not only bones but  impressions of skin and other soft tissue. Vertebrate bodies are preserved in exceptional detail. The pterodactyls at Solnhofen often have fossilized wing membranes. Crustaceans and mollusks are often fossilized as complete bodies. Even the most delicate  parts of squid – tentacles, eyes, and ink sacs – are recorded as high-resolution impressions.

Solnhofen lithographic stone has captured a more complete picture of Jurassic life than any other kind of sediment. Fossils are not common – hundreds of rocks slabs must be split to expose a single animal. Fortunately, the discovery of fossils is encouraged by commercial interests. Beginning in 1798, the lithographic stone has been quarried to make stone plates used to print high-resolution images of paintings, etchings and, later, photographs.

Many scientific publications about Solnhofen fossils have been illustrated by drawings of specimens reproduced via lithographic limestone plates.

Why are Solnhofen fossils so magnificent? The environment  around a tropical reef  was perfect for preservation. Reef-building organisms – sponges, microbes, corals – built up an arc of hard calcium carbonate that shielded a quiet lagoon. All manner of salt-water fish and invertebrates hunted for food in the upper warm waters. Land-living animals came to the beach to search for washed-up carcasses. In the air flew ‘dactyls and, on occasion, a  bird.

When an animal died and sank to the bottom of the lagoon, the water chemistry offered protection from  the forces of decay and dismemberment. The hot tropical climate concentrated the salts in the quietest part of the lagoon, so that most decomposers – organisms that would destroy the carcass – were kept away. Salt-loving microbes spread a thin film over the bottom, and this film functioned like a death-shroud, further protecting the body of dead animals. Perfect fossils were formed when the microbial mat excluded every crab, snail and  bottom-living shark that would otherwise destroy the body.

Extinct Sea Turtle
Eurysternum Wagleri

Solnhofen brings to us a picture of half-way evolution. The rich fish fauna was being modernized by natural selection. Old-fashioned armored fish were going extinct. New styles of jaws and fins were being developed among what would become the dominant fish families in the modern world. Many Solnhofen fish were living-fossils in their own day, representing evolutionary designs that had first appeared two hundred million years earlier. Other Solnhofen fish were the first successful members of clans that dominate today.

Pterodactyls and sea-reptiles too were about half-way in their Darwinian trajectory. Sea-turtles had not yet evolved their specialized flipper. Sea-crocodiles were about to suffer extinction and replacement by the new ocean-going species of the Cretaceous Period. Crustaceans were starting the wave of evolution that would continue as modern crabs and shrimp and lobsters.

There collection displayed here in our exhibit is one of the finest samplings of the entire Solnhofen biota. The Archaeopteryx at the center of the exhibit is the only Archaeopteryx in the New World.

Diplocaulus: The Boomerang-Head Amphibian

 Super-sized “Boomerang-head”
amphibian from
290 million years ago

The Houston Museum of Natural Science has just excavated the complete skull of one of the most bizarre animals that ever lived – the amphibian Diplocaulus. With a head shaped like an armor-plated banana, or an Australian boomerang, this distant kin of today’s salamander is so famous that it stars in most kids’ books on dinosaurs – and in college textbooks as well.

The Boomerang-Head (my favorite nickname for the Diplocaulus) was only of modest size – twenty pounds live weight would be an average adult. But since the first discovery in 1878, the extraordinary cranial design has flummoxed the best paleontological minds. Baby Boomer-Heads had a normal salamander-oid shape, with a rounded snout lined with needle-sharp teeth ideal for snapping up worms on the bottom of ponds.

Weirdness entered the growth cycle as Diplocaulus approached adolescence. The rear corners of the skull grew much faster than the rest of the head, so when adulthood was achieved the head was three times wider than long. And the skull corners became pointed horn-like devices composed of thick, dense, armor-like bone material.

No species alive today comes even close.

What did Boomerang-Heads do with their strange skulls?  Theories abound. Perhaps they plowed up crustaceans hiding in freshwater ponds. Perhaps they used the heads as hydrofoils for flying in river currents. Or for staying put on the bottom during floods. The notion I favor is that the adults whacked each other during courtship battles.

More mysteries surrounded the biggest adults. Heads a foot across are common – but a few incomplete specimens showed creatures 30% bigger. Did the giants represent old males who hid in specialized habitats? Or Boomerang-Head matriarchs?

When HMNS began its long-term field survey of Red Beds near Seymour, Texas, getting  Boomerang Heads for the new Fossil Hall was a top priority. Museum crews did find many parts of mid-sized specimens. Many had evidence of being chewed up and dismembered by predators. Who ate Boomerang Heads? Teeth shed during feeding identified the culprit. It was the Dimetrodon,  a reptile close to the direct ancestry of warm-blooded mammals, including us.

No one in the museum field party hoped for a complete Boomerang Head skull of record size, until……

……Kathleen Zoehfeld, long-time museum volunteer and award-winning author of kids’ science books, scouted a shallow arroyo cut into brick-red pond deposits. Boomerang Head bones were everywhere – including neck vertebrae of gigantic size. Then Zoehfeld spotted the front edge of a skull poking out of the rock. Not just a partial specimen of the sort found elsewhere but the entire head, complete from eye-sockets to horn tips.

Zoehfeld christened the specimen “Geoff” in honor of her son, a sophomore at Columbia University.

Geoff’s head was 16 inches or more wide, as big or bigger than any other noted in paleontological journals. And beautifully preserved.

As soon as I saw it, my mind jumped…I could see how Geoff’s skull would star in the Red Beds tableau of our new exhibit. It would make everyone, kids and adults, stop dead in their tracks and stare.

I took charge of cleaning the specimen personally. It’s 90% done. Our friends at the Black Hills Institute will make casts to share with other museums.

And about those mysteries regarding giant Boomerang heads: HMNS is gathering more clues. Parts of several other giant skeletons were secured near Geoff’s site, suggesting that a sort of “old Boomerang men’s club” might have existed in Red Beds time. Or, alternatively, an amphibian-matriarch society.  Skulls were accompanied by evidence from the other end of the animals – beds full of coprolites (fossilized feces) that may well have been produced by big Boomerang-Heads.

We don’t have the final answers. But the new finds will help. Maybe we’re getting closer to understanding these wonderful critters. And the exhibit of bones and coprolites will delight the scientific imagination of museum visitors.

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