Saltwater SWAT team: Top 5 fascinating shark hunting techniques

I’ve been entranced by sharks since I was a little kid. From the first time I saw Jaws, I was hooked (pun intended). There are so many aspects of a shark’s physiology I admire, but my favorite point of fascination is probably the variety of hunting techniques they use to capture their prey. Though most of my friends are aware of my sharktastic obsession, others are surprised because I’m, well, a vegetarian. Yes, I’m a vegetarian with an intense interest and, dare I say, admiration for this aquatic carnivore’s feeding habits. This animal’s intelligence, grace, stealth, and prowess are unparalleled on land (except maybe when J.J. Watt is playing for the Texans). When people hear the word “shark,” they typically picture mindless killing machines, but they couldn’t be further from the truth. Sharks have highly adapted hunting strategies that have been honed over millions of years to make them one of the most efficient predators on the planet. Here is my own personal countdown of the most fascinating shark hunting methodologies.

mako shark

Mako shark, Isurus oxyrinchus.

Photo credit.

5. Mako shark (Isurus oxyrinchus): Mako sharks are one of only a few shark species that are technically endothermic meaning they are able to maintain a fairly high internal body temperature roughly seven to 10 degrees above that of the water around them. This high body temperature gives them the energy they need to maintain a constant swimming speed of up to 35 miles per hour and bursts of speed of up to 70 miles per hour. The symmetry of their caudal fin also helps them maintain these high speeds. Due to this unique adaptation, Mako sharks are the fastest shark species out there making them a lethal predator. Though they’ll eat a number of different oceanic species including cephalopods, dolphins, and sea turtles, they can also chase down some of the fastest schooling fish in the sea like tuna and swordfish.

whale shark

Whale shark, Rinchodon typus.

Photo credit.

4. Whale shark (Rinchodon typus): Whale sharks get bragging rights as the largest fish species in the world. And while they can grow more than 40 feet in length, their food of choice is plankton. That’s right, ladies and gentlemen, the largest fish species in the world feeds on tiny plankton. As a filter feeder, they swim through the ocean with their mouths wide open to filter out these delicious little morsels and any other small fish that make the mistake of getting in the way. Getting out of the way isn’t always the easiest feat though, since a whale shark’s mouth can open to almost five feet wide!

3. Bull shark (Carcharhinus leucas): The bull shark is definitely a contender when it comes to most fascinating hunting techniques. One of the main reasons for this is its increased territory and hunting ground; it’s one of the few shark species known to habitually hunt in freshwater. When it comes to hunting, bull sharks get their name from their use of a technique known as the bump and bite. Bull sharks will use their body weight to propel themselves into their prey to stun or even kill it. Then, before the prey has a chance to recover, the bull shark attacks. Their unique ability to adapt to freshwater environments means they also have a wide range of prey from sloths to cows to hippos! They are extremely territorial, so they are one of the most common offenders when it comes to shark attacks on humans. Rule of thumb: if you’re in a murky body of water and you feel a hard bump, maybe get out of the water for a bit.

Bull shark

Bull shark, Carcharhinus leucas.

Photo credit.

2. Great white shark (Carcharodon carcharias): Of course, I had to include the famous great white shark. Great whites are probably the most well-known shark, because they have the best agent. Or maybe it’s because almost any movie about a killer shark stars the great white. While many of these Hollywood depictions have led the general public to believe these animals kill without discrimination, they are actually exceptionally precise and calculating hunters. Great white sharks utilize two hunting practices that, when put together, make them an aquatic force to be reckoned with. The first, known as spyhopping, is predominantly seen in marine mammals like dolphins and whales.

Spyhopping is when an animal brings its head above the water’s surface to take a look at their prey. The great white shark is one of the only shark species that we know of that to utilize this technique. After their recon mission, great white sharks travel below the surface to wait for the opportune moment to seize their prey. To capture fast-moving marine mammals (their favorite blubbery snack), great white sharks travel at incredible speeds and explode through the surface of the water. This practice is called breaching, and it’s most impressive when you consider the size of these predators. Great white sharks can weigh up to 2,000 pounds and burst out of the water at speeds up to 40 miles per hour. Some can even reach heights of 10 feet above the water’s surface! It’s a fairly rare occurrence, because it takes considerable energy to propel these animalistic torpedoes out of the water.

 

1. Thresher shark (Alopias vulpinus): By far, my favorite hunting technique of any animal. For decades, fishermen claimed that these sharks used their caudal fin to hunt. They would consistently find thresher sharks caught in their hooks; however, the sharks weren’t hooked by the mouth, they were hooked by their tail fin. Their conclusion was that the unusual shape of this shark’s tail fin was a prominent and integral part of its hunting technique, though they weren’t sure how. Thresher sharks are easy to identify, since they have a highly elongated upper lobe on their caudal fin. This caudal fin can sometimes make up two thirds of the shark’s body length. It has only been throughout the last few decades that researchers have come to witness their amazing hunting technique in the wild. Thresher sharks can actually use their caudal fin like a whip to stun their prey before going in for the kill. It’s a truly remarkable hunting strategy that you have to see to believe!

Don’t forget to stop by the museum’s Shark! exhibition this summer to get a chance to learn even more about these amazing animals. You can track sharks, learn about how researchers tag and study great whites, and touch live epaulette carpet sharks and white-spotted bamboo sharks at our touch tanks, open through Sept. 7.

Still not enough saltwater for you? Drop by the brand-new Hamman Hall of Texas Coastal Ecology, opening this Friday, May 22.

Ants in your Plants: Mutualism benefits both myrmecophyte and insect

What is an “ant plant”? Because we are striving to portray a “real” tropical rainforest, we have several and plants at the Cockrell Butterfly Center, but what makes them so special? Technically called myrmecophytes (from the Greek myrmeco – “ant”, and phyte – “plant”), these plants have a very special relationship with ants, one that is beneficial to both parties. Such mutually beneficial partnerships are known as symbioses or mutualisms, and they are fascinating to evolutionary biologists, ecologists, and lay people alike. So-called “ant plants” typically provide shelter, and sometimes food as well, for ants, and the ants taking advantage of these resources in turn defend the plant against herbivores or other threatening animals, and sometimes even against competing plants. In some cases the ants may provide their host plant with nutrients.

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Ants take shelter inside the passages within the swollen stem of this  Hyndophytum formicarum.

Examples of ant plants abound, particularly in the tropics. They occur in many different families of plants, and involve many different species of ant. Some plant-ant combinations are specific – i.e., the plant has co-evolved with a specific species of ant. In such cases this ant is usually found nowhere else: it has an obligate mutualism with its plant host.  Often the plant has difficulty surviving on its own as well.

More common are facultative mutualisms, where plants provide a resource (usually food) that a variety of ant species may visit. Simply by virtue of their presence on the plant, these ants discourage (or attack) herbivores or other organisms that might harm the plant.

Hundreds of plants bear extrafloral nectaries. These nectar-secreting glands on structures outside of the flower (usually on leaves or the petioles of leaves) are typically most active on new growth, which most needs defense against hungry herbivores. Ants gather at the nectaries to collect the sugary fluid they exude, and kill or chase off insects that try to eat the leaf.

extrafloral nectaries

Ants taking nutrition from extrafloral nectaries on an Inga leaf.

Less common, but still with plenty of examples especially in tropical areas, are plants that provide shelter for ants. These domatia may be hollow stems, swollen petioles, or other hollow spaces on the plant that ants can use as living space.

A few neotropical shrubs in the large genus Piper (black pepper family) have evolved large, envelope-like petioles that house a species of Pheidole ant. Tiny pearl bodies (lipid-containing food bodies) are produced on the inside surface of these domatia – at least when the ants are present. These tiny ants are not aggressive and would not seem to be very effective defenders of their host; however, they have been observed removing insect eggs and small larvae. The real benefit to the host plant appears to be the extra nitrogen that the plants absorb from waste (feces, dead bodies, and other debris) left by the ants inside the petioles.

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Ants taking shelter within the domatia of a Miconia petiole.

Two shrubs in the coffee family, Hydnophytum and Myrmecodia, have very large and complicated domatia. The stems of these epiphytes from the mangrove forests of tropical Southeast Asia and Australia are lumpy and swollen, and almost look diseased. These bizarre-looking structures are riddled on the inside with hollow chambers, much like a Swiss cheese.  If you cut one of the tubers in half, you will find that some of the chambers have smooth surfaces, while others have darker, rough surfaces. The inhabiting ants use the smooth chambers for living space and the rough chambers for dumping their trash. Biologists have observed that the rough-walled chambers are able to absorb nitrogen and other nutrients from the decomposing wastes deposited in them by the ants, while the smooth-walled chambers are not absorbent. Since it is always a challenge for plants without roots in the ground to get enough nutrients high up in the treetops, this is a great adaptation to enhance these epiphytes’ survival. And, not only do the ants provide the plant with extra nutrition – their presence serves to deter things that might eat it.

ant acacia

Enlarged and swollen stipules on an ant acacia offer shelter for a colony of Pseudomyrmex, an ant species found nowhere else but this plant.

The ant-plant mutualisms that really capture our imagination are those obligate mutualisms where the plant provides both food and shelter for the ants, and the ants are particularly fierce defenders of their plant host.  One of the most famous ant-plants is the bull-thorn acacia from the dry forests of Central America. Acacia is a very large genus of plants in the legume family, especially abundant in dry tropical areas of the world. All Acacia species are characterized by having their paired stipules (little flaps of tissue at the base of each leaf, found throughout the legume family) modified into spines or thorns. In the Acacia species associated with ants, these thorns have become very large and swollen, resembling a pair of bull’s horns. A specific species of stinging ants in the genus Pseudomyrmex has evolved as an obligate mutualist of these acacias.  Worker ants make a small hole at the tip of one of the horns, hollowing out an interior, and the colony lives inside these chambers. These ants are found nowhere else.

The bull-thorn acacia also provides its ant inhabitants with food. Like many legumes, acacias have extrafloral nectaries. In this case, they take the form of little slits along the main rachis of the compound leaf. Ant-acacias don’t just feed their ants sugar, however; they also produce small, protein-rich food bodies for the ants on the tips of the new leaflets. The ants thus have all their needs for shelter and food provided by their host plant. In return, the ants vigorously defend their home against anything that threatens it – leaf-feeding insects or other animals – swarming out of the thorns and stinging the intruder. Because these ants also bite and sting any plant that touches or grows too close to their home, they reduce competition to their host from other plants as well, and because tropical dry forests often burn, the vegetation-free circles around the ant-acacia may be particularly important as a fire brake.  Evidence for how much bull-thorn acacias rely on their fierce little ant defenders can be discerned by tasting the leaves. While most Acacia species are full of bitter compounds, ant-acacias have little need to maintain these chemical defenses, and no longer produce them. Their leaves are not bitter. But if the ant-acacia should lose its ant colony, it is liable to be hit hard by hungry herbivores.

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A species of Azteca ants takes shelter inside the hollow stems of Cecropia plants like this one.

The famous British naturalist Thomas Belt first described this amazing symbiosis, which he observed during his sojourn in Nicaragua in the mid 1800s. Today the food bodies borne at the tips of the new leaflets are called “Beltian bodies” in his honor.

A similar scenario, also from from the Neotropics, is seen in the relationship between several species of Cecropia (a fast-growing, early successional tree) and a species of Azteca ants. Cecropia has hollow stems – with special thin skinned “dimples” in the stem opposite each leaf.  A queen Azteca who finds a young Cecropia not yet colonized bores her way through this thin spot (called a prostoma).  The eggs she lays inside the stem hatch into worker ants, who tunnel through the membranes that divide the stem at each node, and open up more of the prostomata, giving them access to the outside. As the tree grows, the colony moves upwards, eventually making the whole tree a long, hollow shelter for the colony. Cecropia trees also provide food bodies for the ants; these “Mullerian bodies” (named for another 18th century European biologist, Fritz Muller) are produced on special spongy structures at the base of each leaf petiole. The occupying ants also bring small homopterans (aphid relatives) inside the stems of the Cecropia, where they feed on the plant’s sap in a protected environment.  The ants milk these small insects for their sugary exudate (called honeydew) just like farmers milk cows. Azteca ants do not sting, but they can bite, and the workers swarm out in huge numbers to attack any animal that touches their plant.

hollow stem with ants

Cutting into a hollow stem shows just how extensive the ant colony runs inside this plant.

A relationship very similar to the New World Cecropia-Azteca mutualism is found in the Old World tree Macaranga, also an early successional species, but in the spurge family, a completely different plant family from Cecropia. The ants inhabiting these plants are members of the ant genus Crematogaster (unrelated to Azteca). This is a great example of what is called convergence in evolutionary terms, whereby similar situations in different locations give rise to the same adaptive solutions among unrelated organisms.

Ants are amazing little creatures, and their complicated social behaviors, which often seem to mimic ours, make them particularly good partners for plants in the fight for survival.

Look for the bull-thorn Acacia (sans ants, unfortunately) next time you visit the Cockrell Butterfly Center. We recently received a specimen of Hydnophytum and of Mymecodia from a generous donor. These will eventually be placed in the rainforest. Our Cecropia tree, alas, got too big and died a few years ago. We hope one day to replace it!

 

Why you should care about endangered species today, tomorrow, and every day

The truth of the matter is that we humans are bound to this Earth. As the dominant species, it is easy for us to allow industry and propaganda to run rampant, annihilating whole populations of the animals with which we share the environment. One shepherd will kill the wolf who threatens his flock, one company will dynamite a mountain to extract an ore, and that may be fine. But if all the shepherds and all the companies kill and dynamite at once, that is a menace to the natural world. And as long as we continue to take advantage of quiet places virgin to human feet, or villainize an animal as a man-eating monster, the diversity of life on earth will always be in danger.

howl

A red wolf specimen behind glass appears to be mourning the loss of endangered and extinct species in the case beside it, in Texas, and across the globe. Farish Hall.

The question you have to ask yourself on Endangered Species Day, and every day, is are we really still competing with animals to gain a foothold on this rock we call home, or are we simply the most ruthless? One death by mauling, even 10 or 20 or 120, does not constitute a credible threat to humanity; there are billions of us. Call a shark, a bear, a wolf, a lion, a panther, any apex predator a danger to one or a small group of humans, but the time of fighting to survive in the jungle has passed. True, African villagers still suffer casualties due to contact with lions; yes, trekkers in the Rocky Mountains must remain vigilant for cougars and bears to avoid attacks; and yes, 10 people were killed and 87 were injured worldwide by sharks in 2014, but modern humanity now has the power to slaughter every last individual of any species. It’s not that difficult, and often it’s due simply to the spread of our kind into wild areas for resources or human development.

ocelot

Less than 1,000 ocelots are thought to survive in the wild. Farish Hall.

In the case of sharks specifically, 97 casualties in 2014 does not and cannot ever justify 100 million sharks killed every year. That’s about 274,000 dead sharks a day, or 11 shark killings per hour. A shark dies at the hands of a human, somewhere, every six minutes. Even nuisance animals aren’t this systematically destroyed. The World Wildlife Fund lists great white sharks as vulnerable on their endangered species directory, facing high risk of extinction in the wild. We don’t know much about shark biology and behavior, but we do know they play an important role at the top of the marine food chain, according to the WWF. They might all die before we get to know them.

prairiechicken

Attwater’s greater prairie-chicken exists now only in wildlife refuges. Farish Hall.

Sharks aren’t the only species in danger, of course. Many other animal populations have dwindled to mere hundreds. Biologists count 880 mountain gorillas left in the Virunga Mountains of central Africa. Imagine having only 880 humans on the planet. That’s barely the size of a small town in Texas, one of those places Grampaw says you’ll miss if you blink as you pass by. As few as 3,200 tigers live in the wild across the planet, the WWF says, and giant pandas, the mascot of the organization since 1961, number just above 1,800. Our favorite mammals are nearly gone. Just as gone as the dinosaurs. When they’re gone, they will never come back. Ever.

jaguarundi

Native to southern Texas, the jaguarundi is one of many endangered predators. Farish Hall.

In Texas, from the pounding Houston rain to the burning sun of El Paso, the steamy barrier islands to the prairie grasslands and canyons in the panhandle, it seems the big sky country has enough space for everything. But farming and introduction of non-native species, as well as the urban sprawl surrounding our boundless cities, has built a long list of endangered species. Texas Parks and Wildlife lists the Kemp’s Ridley sea turtle, the Attwater’s greater prairie-chicken, the wooping crane and the red-cockaded woodpecker endangered in Harris County, as well as the red wolf, the smalltooth sawfish, the Houston toad, and the leatherback sea turtle. Some of these exist only in wildlife refuges.

bigwoodpecker

The ivory-billed woodpecker, native to Texas, is critically endangered and thought to be extinct. Animatronic specimen displayed in Farish Hall.

The concrete city landscape of Harris County has replaced the natural habitat, a corner where coastal, wetland, and piney forest environments merge. As the city expands, roaming species like the red wolf are pushed out of their home territories while their numbers decline, but other creatures that rely on this area specifically for the resources the environment provides simply fade away. The Kemp’s Ridley feeds only in muddy or sandy bottom habitats, those brackish areas where swamp meets seawater, and while they migrate across the Gulf, these turtles still require coastline to nest. Other migratory species like the whooping crane use the coast as winter breeding grounds. As development continues, these environments shrink or change enough to kill off such species.

parakeet

The Carolina parakeet, once native to Texas and most states along the eastern coast of the United States, was declared extinct in 1939. Farish Hall.

Texas used to have its own native parrot, the Carolina parakeet. This beautiful tropical bird with red, yellow and green feathers, suffered devastating losses from deforestation and feather-hunting. It was declared extinct in 1939. Its range extended in the eastern United States from New York to Texas. The Houston Museum of Natural Science has a mounted specimen on display in the Farish Hall of Texas Wildlife, alongside many other examples of native and endangered species. Apart from taxidermy, this parrot exists only in the imagination.

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The endangered red-cockaded woodpecker is losing its habitat in Texas due to loss of the piney woods environment in which it lives and hunts. Farish Hall.

Next week, HMNS guests concerned about endangered species can come to the Hamman Hall of Texas Coastal Ecology, a new permanent exhibit adjacent to Farish Hall opening May 22, to learn more about the relationship between the environment and the economy. Some of Texas’s iconic species, including rare and endangered plants and animals, will appear on display. After touring these exhibits, visit the 100 awe-inspiring images of the 50 Years of Wildlife Photographer of the Year display. Some of these, like the photos of legal lion hunting, hyenas eating from a human garbage dump, and prospectors destroying thousands of acres of virginal forest for minerals, reveal just how awful things can get when we neglect the natural world.

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A quote by William Beabe in the Farish Hall of Texas Wildlife reminds us why we should care about endangered species.

Why should you care about extinction on Endangered Species Day? Because if a species dies out, it never comes back. Every creature is important, unique in its behaviors or adaptations or the shape and color of its body. If these creatures disappear, the only way we can get to know them is through history and in museums, not through personal experience. We will never know what we could have learned from them. We are the stewards of this planet now, not its owners. We rely on it much more than it relies on us. If we don’t help preserve life, these endangered species are as good as stuffed. And when they all die off, we’re next.

Get wet, go wild, or blast off with new Party Smarty birthday themes at HMNS

by Karen Whitley

Yikes! Is it May already? Time has flown by and now your child is about to turn another year older. Between work, school, dinner, errands, and that never-ending laundry, who has time to plan a party? Lucky for you, that’s what we’re here for! Not for the laundry (you’re on your own with that), but the Houston Museum of Natural Science is the place to call for giving your child a birthday experience he or she will never forget. We have hosted over 3,000 birthdays here at the museum, so we know a thing or two when it comes to parties. This year we are excited to announce that we are offering three new Party Smarty themes at our Hermann Park location: Shark!, wildlife, and Mars expedition!

Shark- Touch Tank 2 (2)

Sharks have always fascinated us land-dwellers, and they continue to hold millions of people across the nation in thrall each year in July. If you have your own shark-lover at home, now’s your chance to become the coolest parent around by throwing your kid aShark- Great White2 (2) birthday party with real sharks! Not only will they get to learn about great white sharks,
see the jaw of a megalodon, and actually get inside a shark cage, but they will also get the chance to touch live sharks in our Shark! touch tank experience. As an added bonus, each kid will get a one-of-a-kind button declaring that they touched a shark. Shark! will be leaving our museum in September, so make sure to grab this chance before it swims away!

Wildlife 7 (Swan Lake) 2Did you know that a ringtail cat is not a cat? Or that a bald eagle has 7,000 feathers? With our Texas wildlife theme, your birthday group will get the chance to hop along with robins and howl with coyotes as you explore the diverse habitats and wildlife that our great state Wildlife 8 (Ocelot) 2has to offer. From soaring falcons to roaming American buffalo, there are more than 250 types of animals in the Farish Hall of Texas Wildlife! Will you be able to find the flying squirrel? Now you and your guests can experience the American wild from dawn to dusk as you listen to the calls and sounds of our animals with the rising and setting of the sun.

Looking for something special for your pre-teen or teenager? Our Expedition Center theme is a great way to get them away from their video games and into a thrilling simulated flight to Mars! This is no pleasure cruise: your teen and friends will have to work together to Expeditionsuccessfully complete their mission to land on Mars. From piloting and navigating to building probes, experiments, and so much more, everyone will have a blast on this voyage into uncharted territory.

For more information about all of our basic and deluxe Party Smarty themes and packages, visit us here.