SHARK!

This post was written by Diana Birney, Supervising Marine Biologist for our upcoming SHARK! exhibit, opening August 29, 2015.

We fear them, we love them, and we are fascinated by them. We have a whole week on television dedicated to them that draws millions of viewers every year. Humans have an amazing obsession with this interesting group of animals, especially considering that we really don’t know that much about them.

It’s clear from the popularity of movies like Jaws and Sharknado that we love to be scared by sharks. While there is a good reason to give sharks their space, they are not the crazed “man-eaters” that Hollywood has often portrayed. In fact, since 1911 there have only been two deaths and less than fifty unprovoked attacks by sharks in Texas.

You’re actually more likely to be struck by lightning than you are to be attacked by a shark.

However, every time you enter a body of water, you should go in with the knowledge that a shark could potentially be there. When it comes down to it, it’s their space — not ours.

That doesn’t mean that you can never go in the water again, it just means be smart about what you do in the ocean…

So go to the beach, bring your sunscreen (and reapply it often!). But also bring your knowledge of what lives in the habitat you are about frolic in. Feel like you don’t know enough? Don’t worry! Here’s a nice set of guidelines for your next trip:

1. Sharks aren’t searching for humans to eat

There is no evidence to suggest that sharks like eating people. In fact, considering the numbers of people that go to the beach and the attack statistics, it would seem that sharks DON’T like eating people. A beach is a potential buffet at certain times of the year, but the sharks don’t seem to take advantage of it (good news for us!).

When people do get bitten, it’s usually one bite and the shark lets go. This is similar to the other night when I had a plate of broccoli I was going to town on and ran into a bite of mushroom (I hate mushrooms). I promptly spit that nasty bite out and went back to my broccoli feast (YUM). Sharks tend to follow schools of fish or, for our larger shark friends, mammals such as seals. Schools tend to frequent coast lines and often when someone is bitten there is a school of fish in the area that the shark was intending to chow down on.

2. Sharks have AMAZING noses

Sharks can sense blood in a ratio of one part per million. They also have sensors on their noses called ampullae of Lorenzini. These are electroreceptors that can sense the electrical field given off by everything swimming around in the ocean — including you and me! If a wounded person or animal enters the water, a shark can be drawn to the blood but also to the electrolytes that pour out of the wound as well.

There is a common idea that punching a shark on the nose will make it less likely to attack you. This stems from the fact that the ampullae are all over the nose and punching the shark might disrupt the electroreceptors. Another reason this (sometimes) works is that most sharks like certain prey items and most of those prey items don’t know how to punch — giving the shark a strong clue that it won’t like eating you. 

However, it’s important to not just go around punching sharks… right under their nose is a huge mouth with lots of teeth, and you may end up just losing an arm instead of scaring the sharks.

3. “There’s a chance I’ll bite if you bother me too long” – sharks

This summer there was a shark bite incident off of the coast of California with a White Shark. A swimmer got too close to a fishing line that caught a shark. The shark had been on the line long enough to be mad at everyone and everything. When the swimmer approached it, unaware it was even there, the shark lashed out. The moral of the story is that sharks, like dogs and cats, have no way to communicate with us that they are uncomfortable or in pain. The only avenue available is their teeth. Many bites are exploratory or just to say “BACK OFF.” 

A good rule of thumb in any environment is that if it has teeth it can/will bite.

4) Stay with your swimming buddy

Having a buddy is essential for beach safety. Rip tides can pull even proficient swimmers down and out into the ocean (and are actually much more likely to happen to you than a shark attack). Sharks, just like other apex predators, e.g., lions, tend to go after prey that is separated from the pack — it makes for an easy dinner.  So if you are swimming alone a shark might think you are a solitary prey item. If you are with someone else, the shark might still think you are prey, but will be less likely to attack a small “pack” rather than a solitary animal.

The buddy system is also beneficial just in case something does happen. Your buddy can get help and report exactly what happened in case you are in shock or missing.

 

5) Daytime is the best playtime

Most sharks hunt at night, dawn and dusk when they can see the best. Fortunately, most people go to the beach during the day. Just be extra careful if you are going out in the evening or at night because the shark can see you better than you can see them, guaranteed. However, if you are in an area frequented by White Sharks remember that they tend to hunt during the day when their traditional prey are more active.

6) Play smart

It’s important to know what signs indicate a higher chance of sharks in the area. Sandbars and the drop offs around sand bars are a common shark hang out. Sharks can swim in extremely shallow water, so don’t let the low water level lull you into a false sense of security.

An easy sign of sharks to watch out for is the presence of other animals. I know it’s hard to stay back when you see a bunch of fish in the water (as a Marine Biologist, I can be guilty of not staying away from schooling fish), but sharks enjoy snacking on large groups of fish. We wouldn’t want you to end up a morsel in the shark’s buffet.

However, we can’t always see schooling fish. Don’t worry too much since there are more obvious signs you can watch out for including: birds, dolphins/porpoises and lots of splashing. Birds will attack schools from the air, so if you see many birds diving in a particular spot, you can safely assume there are fish there and will want to stay away from that location. Same with dolphins and porpoises. They eat a lot of the same foods that sharks eat, so do not assume there are no sharks just because you see dolphins.  Splashing is also a key sign to sharks that prey is in the area since schools of fish tend to ascend and splash around near the surface. So, again, stay away from areas that show signs of splashing, and it’s also a good idea to keep your splashing around to a minimum.

7) Know your local sharks

It’s also good to know your local sharks. The Gulf of Mexico is home to many different species, some sharks you might not see — much less have to worry about. Others, like the Bull shark account for all of the Texas deaths from sharks (don’t be too alarmed, again, there have only been 2 since 1911). We also have thresher (my personal favorite shark), nurse, blacktip, tiger, many different hammerhead species, and many more.

If you followed the news this summer, you might have seen a White Shark named Katherine approaching Texas. Katherine shows us that we can get Great White Sharks in the Gulf. For more information on Katherine and many other tagged sharks you can go to OCEARCH.org. If you are travelling and plan on going to the water, it’s helpful to know what sharks are in the area and how likely your are to see them.

In the long run, it’s important to remember that shark interactions are NOT common, you just want to be prepared and armed with knowledge whenever you hit the beach.

The Houston Museum of Natural Science is teaming up with the Texas State Aquarium and OCEARCH to bring more information and awareness of sharks to Houston with our new SHARK! exhibit

Come visit to learn about (and even touch!) these amazing animals starting August 29!

Swept away by Sharknado: Taking a bite out of our shark fears

Unless you’ve been living under a rock for the past year (if you have, congrats! You made it back!) you’ve probably heard of a little genius of a film called Sharknado (playing this Friday, August 8 in the Wortham Giant Screen Theatre).

As the title implies, it’s about sharks and tornadoes — more specifically, water spouts off the coast of southern California which wreak havoc on L.A. as they flood the city while simultaneously picking up and distributing ravenous airborne man-eating sharks — and a motley crew, including the one and only Tara Reid, who defies the terror of the sharks to save the day. It’s a classic tale of guy meets girl, guy and girl fall in love, guy and girl get divorced, sharks attack, guy gets girl back.

Why Sharknado got snubbed at the Oscars, I’ll never know.

Now I must admit I was a little apprehensive of the film when I first heard of it. As a child who saw Jaws too soon (also showing in the GST this month), as you may have been as well, you hear the word “SHARK” and feel something like this…

And who can blame you?! Negative images of sharks are everywhere. But they actually haven’t been around for all that long. At the turn of the 20th century, most people believed that sharks had never attacked a human being. Now, we know that occasionally this does happen. There were 7 people who died from shark attacks in the world in 2012 (meaning your chance of being one of those people is literally less than one in a BILLION). Compare that to the 33,561 people who died in car accidents in the U.S. in 2012. So the early 20th century perception is actually closer to the truth than modern perceptions (most people believe their risk of getting eaten by a shark to be much, much higher).

So what happened?

In the summer of 1916 there was a horrifying case of a rogue great white shark that ate several people along the New Jersey coast, and the event received a lot of press. Then during WWII, stories of shipwrecked sailors and others stranded in the ocean getting eaten by sharks began to permeate popular culture. All of which helped to set the stage for Jaws to come along and scare the pants off America.

In this movie, Spielberg really hit a chord with American audiences; just think about how much this movie has seeped into our collective consciousness. Everything from the opening music, Baaa-da. Baaa-da. Ba-da ba-da. Ba-da-ba-da-badabada…, to the line (from the sequel’s trailer, mind you) “Just when you thought it was safe to go back in the water…” that sends shivers down our spines.

“So why should we watch Sharknado?” you ask, “Isn’t this just perpetuating irrational fears about getting eaten by sharks?” Perhaps, but consider this: Sharknado presents the perfect way for us to get over our fear of sharks.

By taking this fear and placing it in the most ridiculous context ever, in a low budget B Movie, with a plot full of holes so big you could drive a truck through them, we can remove ourselves enough from the situation to have some perspective. When we watch Sharknado we can laugh at our fears while watching a rollicking, action-packed film full of spectacle and get swept away (pun intended) into this fantasy world.

Jaws took place in our backyard, Sharknado in some alternate universe where Tara Reid is still an ingénue.

When we leave the theatre we aren’t scared of the world around us, we’re too busy taking in the unabashed ridiculousness of the film, tweeting our friends all the way home.

So let’s take a bite out of our crazy irrational fears and embrace Sharknado for the awesome cultural phenomenon that it is Friday, August 8 at HMNS!

In case you need some more convincing, watch the trailer below! Want to learn more about how awesome sharks are? Come to HMNS starting August 29 for our SHARK Exhibition!

 

 

Shark Week turns 25: Our six ways to celebrate

It’s the most wonderful time of the year, guys and gals: Shark Week is back.

After falling deep down the wormhole of the Summer Olympics (or as we like to call it, the Swimmer Olympics), it’s nice to have something else sleek and muscular to watch in the water.

So in honor of this horrific holiday season of sorts, here are six ways to celebrate Shark Week, starting Sunday, August 12:

1. Make a ridiculous watermelon sculpture, and try not to scare the bejeezus out of your kids.

Shark Week 2012

2. Imagine if sharks could fly and never sleep again.

Shark Week 2012

3. Imagine sharks had movie star teeth and feel better.

Shark Week 2012

4. Have mixed emotions about this photo:

Shark Week 2012

5. Be glad this guy’s extinct:

Megalodon Jaws

6. Learn more about the fiercest shark that ever lived and rent Mega Shark Versus CrocosaurusJust kidding — visit our new Hall of Paleontology to see a cast jaw, spectacular paleo art by Julius Csotonyi, and a compelling display of the jaw with the prey it’s poised to consume.

Happy Shark Week!

What a Croc!

Today’s guest blogger is Neal Immega. He has a Ph.D. in Paleontology and is a Master Docent here at HMNS. In his post below – originally printed in the Museum’s volunteer newsletter– Neal discusses the Geosaurus, a fossil featured in our exhibition Archaeopteryx: Icon of Evolution.

The Houston Museum of Natural Science has a new exhibit, “Archaeopteryx: Icon of Evolution” that features the best Archy ever.  Do not let that blind you, though, to the other critters on display. One of these is the best marine crocodile anywhere, a Geosaurus with an exciting evolutionary story all its own. These animals have a worldwide distribution from Brazil to Germany, but this specimen is the most complete, and shows the soft parts. Ah, the preservation of fossils in the Solnhofen limestone is amazing.

Let’s see what observations we can make from the skeleton and what conclusions we can draw. Look at this picture and get an overall impression of the fossil. The label says it is a croc, but is it? It does not look like any croc I have ever seen.

Complete Geosaurus skeleton, with skin impressions, from the Solnhofen limestone.
Geosaurus skull showing croc dentition

Head: The front end certainly looks like a modern crocodile head. The teeth are conical and striated, with the typical croc dentition:  teeth are located inside and outside the jaw line, and there are large teeth half way down the jaw.  Modern crocs use them for breaking turtle shells (see the YouTube video referenced below).

Tail: Ok, so it is a croc but it does have a very strange tail. Let’s look more closely at the tail to see if there is any support for the decision the preparator made to indicate a tail like a shark’s.

The faint skin impressions support
interpretation as a shark-like tail.

The discolored rock strongly suggests that the tail does have a shark outline, unlike that of all known modern crocodilians. Even better, compare the caudal processes (bumps on the top of the vertebra) in the area of the fin to those farther up the spine.  The processes in the tail fin area are longer and reverse orientation: they point toward the head, possibly as support for the fin. The fin is real!

Armor: This croc does not have any! There are no osteoderms (bony plates inside the skin) anywhere. The osteoderms in modern crocs do not provide complete coverage and thus are not much use as armor; however, a modern croc has muscles between its osteoderms that can stiffen up the skin during rapid land movements.  Apparently Geosaurus got along without them.

Legs: The arms are very short in proportion to the legs, quite unlike modern crocs.

Salt Gland: Many animals have glands to secrete sodium chloride because they live in or on life from the ocean and eat way to much salt. This animal is said to have chambers in the skull for a salt gland, but I cannot see it. I guess I will take their word* for it. A modern croc has a salt gland in its tongue while many birds have theirs in the skull.

Analysis: Modern crocs are slow swimmers and, thus, ambush predators. A shark-like tail suggests this was a higher speed predator. A modern croc has about 5% of its weight in osteoderms and their absence would improve the water speed at the expense of land speed. I think we have caught this croc species in the transition stage of becoming a true marine predator. It still had clawed limbs to crawl out on the land (to mate and lay eggs) but their smaller size would certainly help reduce drag. If this evolutionary path had continued, the croc’s descendants might have ended up looking like Ichthyosaurs, air-breathing reptiles that gave live birth and looked remarkably like modern dolphins. Remember, a saltwater croc in Australia is called a marine crocodile, but it does not have many adaptations to live in the marine environment besides a salt gland in its tongue.

An Ichthyosaur is a reptile completely adapted to a marine environment.
What happens when a Steneosaurus trys to
ambush an Allosaurus at the water hole

There are other crocs found in the Solnhofen limestone, including long-legged land crocs, dwarf ones, and a substantially armored one, Steneosaurus, featured by Dr. Bakker in this wonderful drawing.

To read more about the Geosaurus, check out Dr. Bakker’s blog.

References:

Wikipedia:  Criosaurus , Dakosaurus, Geosaurus
A nice discussion of aquatic crocs is at  http://en.wikipedia.org/wiki/Cricosaurus

Modern croc using those teeth on a turtle: “ahmedsadat” posting on YouTube, 2008, “Crocodile eats turtle”,  http://www.youtube.com/watch?v=cSKAXOFvi6c

*Salt glands – it is claimed that the skulls have a chamber for salt glands see Fernández and Gasparini, 2008, Naturwissenschaften. 2008, 95(1):79-84. Epub 2007 Aug 22. http://www.ncbi.nlm.nih.gov/pubmed/17712540

Dwarf crocs from the Solnhofen limestone, page 36 in Wellnhofer, 2009, Archaeopteryx, Icon of Evolution, Verlag Dr. Friedrick Pfeil.

All pictures by Neal Immega except the Dino/Croc fight which is by Dr. Bakker.