Tawny Nurse Shark

A group of tawny nurse sharks (Nebris ferrungineus) circling each other at dusk. This behaviour may be related to reproduction, the female, top, looks heavily pregnant in this photo and the male, below, might be able to sense she is soon to give birth. Note in the background there is another group of sharks circling each other. Photo by Alexander Mustard, for more go to www.amustard.com

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Orectolobiformes
Family: Ginglymostomatidae
Genus: Nebrius
Species: Nebrius ferrugineus

I have this kids’ picture book that illustrates 1000 things you can find in the sea, and I use it on occasion to decide what I’m going to research next. I haven’t written about a shark in a while, so I decided to research the Tawny Nurse Shark, also called Nebrius ferrugineus. Though to her friends, she’s referred to as Madame X…

I wish I was kidding about the common name Madame X . Supposedly, the common name was coined in the 1930s by a shark fisherman that found a specimen in Australian waters; before then, it had not been recorded in those areas.

The tawny nurse shark is located in the Indian Ocean, and the in western and southwestern areas of the Pacific Ocean. This shark hangs out near or on the bottom in sheltered areas, including lagoons, channels, seagrass beds, caves on the outskirts of coral reefs, crevices in coral reefs, and right off beaches. They sleep together in secluded areas during the day and hunt for prey at night.

Around the mouth, tawny nurse sharks have barbels—whisker-like appendage—that help them sense prey. They eat small fish and benthic organisms (creatures that live on the seafloor), including crustaceans, sea urchins, and some cephalopods. When it finds potential food, the shark creates a suction to pull the prey out of hiding and into its mouth, where comb-like teeth help to break up hard shells.

This is a pretty docile shark. Divers consider it a favorite because the shark allows the divers to approach it, even touch it. However, when harassed, it will fight back and has been recorded to cause non-fatal bite injuries.

Please do not touch sea creatures unless you have the specific training to do so! You would lash out too if a stranger came up and started putting their hands all over you.

Tawny nurse sharks are considered vulnerable to extinction by the IUCN Red List, and their population numbers are declining. They have a limited home range, so their immediate environment is very important to them. Some populations are declining due to overfishing of the nearby reefs. Some sharks get caught up in gill nets and die as bycatch.

Bycatch refers to any creature that isn’t the target of the catch. So if fisherman are using nets to catch tuna, then anything that isn’t tuna that gets caught up in the net is considered bycatch. Typically, bycatch is thrown back into the ocean, whether it’s alive or dead, because most fishing boats have a bycatch limit.

Tawny nurse sharks are also considered game in some countries. Their “fighting spirit” and strength make them a popular shark to fish for, especially in competitive fishing. Some areas will eat the meat of the tawny nurse shark and ship the fins to Asian countries.

If we’re not careful, this is another species of shark that can disappear before we know it, especially since it has a low reproductive rate. A balance between the fishing industry’s needs and proper fishing regulations must be found in order to address this issue.

Sources and links:
Ocean the Definitive Visual Guide made by the American Museum of Natural History
https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/nebrius-ferrugineus/ ⇐lots of information
https://www.sharks.org/tawny-nurse-shark-nebrius-ferrugineus ⇐brief overview
https://www.fishbase.de/summary/Nebrius-ferrugineus.html
https://fishesofaustralia.net.au/home/species/1974#moreinfo ⇐talks about the Australian populations
https://www.iucnredlist.org/species/41835/10576661

Advertisement

Shark Bay, Australia

All right, ladies and gents, last week we chatted about Shell Beach in Australia. For this week’s adventure, we’re going to pack up our fins and snorkels and head to Shark Bay again, but this time we’ll focus on the area as a whole. And remember, please keep your hands to yourself and watch where you put your feet; we are guests in their environment, and we don’t want to accidentally poke a shark!

Shark Bay is located on the most westerly point of the Australian continent and has been recognized as a UNESCO World Heritage Site since 1991. The protected area covers about 2.2 million hectares. That’s a lot of area, but how do you visualize that?

Well, Shark Bay is about the size of 2.2 million rugby fields, or baseball fields, smashed together in one giant area. If you’re not a sports fan, then visualize Shark Bay as being about the size of New Jersey and roughly half the size of Switzerland. Anyways, that’s a lot of protected area, and 70% of it includes the surrounding marine waters.

Many aspects make this area unique.

It has one of the largest, most diverse seagrass beds in the world with at least 16 different species of seagrass. It’s one of three places in the world where you can look at stromatolites, which I’ll talk about later; for now, I’ll just tell you they are one of the oldest forms of life on Earth—they’re like living fossils!

Shark Bay is home to around 200 species of birds, almost 100 species of reptiles, and several marine species, many of which are threatened or endangered. It has a large population of marine life, including dolphins, dugongs, sharks, rays, two species of endangered sea turtles, and two species of whales, not to mention all of the fish and invertebrates drawn to the seagrass beds.

This area is so important to so very many species living on land and in the water, and it gives you an interesting look at biological and geological evolution overtime. This is the perfect place to go to if you love birds, reptiles, plants, or the ocean—I think I could spend a whole week here and still not do everything I’d like to!

There are all sorts of things to do at Shark Bay! You can dive and snorkel in the waters. There’s a marine park, an aquarium, and a national park to explore. There are guided land tours, boat tours, dive tours, and marine safaris! You can see dolphins, whales, sharks, Manta rays, Green turtles, Loggerhead turtles, and dugongs!

You can explore the seagrass bed or the surrounding land area. There’s Shell Beach to relax at and the Hamelin Pool stromatolites to see! There’s so much, and I’m so ready to pack my bags and go myself—if I ever get the money and the time to go. For those of you who can go, please experience this place and maybe share all your cool stories!

Sources and cool links:
https://whc.unesco.org/en/list/578
https://www.sharkbay.org/about/
https://www.australiascoralcoast.com/destination/shark-bay-world-heritage-area
https://oceanpark.com.au/shark-bay/

Sharks up Close by Jim Abernethy and Jennifer R. Nolan

Sharks up Close by Jim Abernethy and Jennifer R Nolan. Photography by Jim Abernethy

I have an interesting habit of buying books and not reading them for an untold amount of time, and that includes my nonfiction library as well. I buy books on sale, when I visit local bookshops and aquariums, or if I have coupons I want to use. I really do want to read the books—I swear! Sometimes my attention gets taken by something else.

Sharks up Close was one of those books that I bought from an aquarium a few years ago, and the other day I finally sat down to read it. The book is written by Jim Abernethy and Jennifer R. Nolan with a forward written by Shawn Heinrichs, another photographer and conservationist. However, it’s not Shawn’s photos that the book uses. All the photography is done by Jim Abernethy himself, and let me tell you, his photos are gorgeous.

I met Jim Abernethy during my early years of college when he had been giving a talk on sharks and his own journey with conservation. His talk was so inspiring, I just had to have Sharks up Close to help show support.

The book is very easy to follow and was obviously written for a younger audience, but I would argue that adults will find it interesting as well. Each topic is introduced by asking a question. The topics range from anatomy to behavior to conservation. The language is very straightforward, they do a wonderful job talking about each topic without using too much technical jargon.

I really enjoyed the question-answer format, because a lot of the questions in the book I’ve been asked by other people. It was very helpful to read and I think it may help out parents as well, especially if their children are enthusiastic about sharks!

Towards the end of the book, it talks about conservation efforts and the nature of shark finning. It’s not an easy topic to read about, personally, I find it horrific whenever I read about the issue. That topic may be tough on some kids, especially with some of the photos. Don’t get me wrong, it’s not terribly graphic but it may upset some of the more sensitive readers. The book ends on a positive note by listing ways in which we can help with shark conservation.

I recommend this book as a gift for anyone interested in sharks. The photography is amazing and the language is very easy to understand. I believe it would be a perfect gift for a child, and an interesting book to read together!

Whale Sharks

A circular fisheye photo of a whale shark (Rhincodon typus) gapes open its mouth while feeding at the surface, in a behaviour known as botella feeding. Photo taken by Dr. Alex Mustard, you can find more amazing photos at www.amustard.com

Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Chrondrichthyes
Order: Orectolobiformes
Family: Rhincodontidae
Genius: Rhincodon
Species: Typus

A good friend of mine from college is a huge shark enthusiast. She could tell you all sorts of facts about sharks and I’d always go to her if I was having a hard time learning various tidbits about them for class. So I hope I do the whale shark justice today, or else I’m sure I’ll get a playful smack for it later!

Whale sharks (Rhinocodon typus) are pretty cool because they’re the largest shark that lives today, which makes them the largest fish too. Sharks belong to the class of cartilaginous fish with skates and rays—yes, skates and rays are considered fish too. Whale sharks grow up to 65 ft long and are typically the size of a school bus. Their mouths are large enough to fit a person inside comfortably, but don’t worry. We’re safe from these gentle giants because they’re filter feeders! That’s right, these behemoths feed on some of the smallest organisms on the food web—plankton and small fish. But how do they get enough food to support their size?

While they cruise around the tropical waters of the oceans they open their large mouths, suck in a lot of water, and push it out over their gills where the food gets stuck on gill rakers. The food sits on the bony projections until it’s later swallowed. Other than their size, you can also identify these guys by the long ridges that run down their bodies and their spot covered skin. In fact, each Rhincodon typus has a unique pattern of white spots that allows scientists to identify different individuals.

Here’s another neat fact about whale sharks. Whale shark mothers carry their fertilized eggs inside themselves and those eggs will hatch inside her, allowing her to give birth to live young. Cool, right? Sharks have a lot of weird birthing processes that I’ll eventually cover, but this process is called ovoviviparous—that’s a mouthful!

I hope I’ve gotten you interested in whale sharks with this piece. I saw my first one a few years ago at the Georgia Aquarium in Atlanta, Georgia. I didn’t know what to expect but it was like love at first sight. They were these big goofy sharks gliding around the large tank, occasionally opening their mouths as they went. They were really peaceful to watch and that’s what I did for hours, letting the people around me melt away as I watched the whale sharks move about and the manta rays danced around them.

It’s sad to know that whale shark populations are declining, even though they’re protected in some countries. Their meat and fins are highly sought after for shark fin soup, and they are hunted in unsustainable numbers. Don’t get me started on the dish, not yet. When you get the chance, take the time to watch these gentle giants and get lost in their goofy majesty.

Sources and cool links:
Ocean: The Definitive Visual Guide made by the American Museum of Natural History
https://www.nationalgeographic.com/animals/fish/w/whale-shark/
https://www.sharksinfo.com/ovoviviparity.html
https://www.georgiaaquarium.org/?rebound=1

Symbiosis

I just wanted to take a quick moment and talk about symbiosis. I know it’s a topic you learn about in school; I first learned about it in middle school, then again in high school biology, and then a few more times in college. If you already know about symbiosis feel free to pick another post from the sidebar or glance over this one for a quick refresh. For those of you who haven’t learned about it yet or have simply forgotten, I’ll try to explain it in the best way possible—through the human experience!

There are many forms of symbiosis that we see and experience every day, but first let me explain what it is.

Symbiosis is any long-term and personal relationship between two or more individuals, and the relationship can be between the same or different species, such as between you and another human or a pet. Each participant in the symbiotic relationship is called a symbiont.

There are different types of symbiosis that are defined by the kind of interactions between symbionts. If you’ve read my post about coral and zooxanthellae, you’ve already been introduced to a form of symbiosis called mutualism. In a mutualistic relationship, such as coral and zooxanthellae, both parties benefit without inflicting harm on each other. Think of mutualism as the relationship you have with a project partner: if done right you both benefit from each other’s hard work. It can also be viewed in a relationship between humans and dogs or cats: the animal gains a home and a reliable food source while, the human gets companionship and additional health benefits.

A female oceanic whitetip shark (Carcharhinus longimanus) is accompanied by a group of pilotfish (pilot fish: Naucrates ductor) as it swims overhead. Photo taken by Dr. Alex Mustard, find more of his photos at www.amustard.com

Commensalism is a type of symbiotic relationship wherein one individual benefits and the other remains unaffected. An example of this is the pilot fish that ride on or near sharks or larger fish: the pilot fish feed on the leftovers of their hosts while the hosts remain unaffected. In the human experience, it’s like when you let a classmate copy off your homework: you gain nothing while they get all the right answers.

Not every relationship is healthy though. And this last relationship may be disturbing for some people.

Parasitism occurs when the parasite benefits from the host and the host suffers. An example of this relationship can be found in all species of parasitic wasps. The wasp will find another insect (caterpillars, spiders, other wasps, etc.), paralyze them, and then lay their eggs inside the host. The host will then go about the rest of their lives while incubating the eggs, and when the eggs hatch, they burst from the host like a scene from the movie Alien. And sometimes the host will survive only to protect the hatchlings until the host dies of starvation. This is an extreme example, but one of the more fascinating ones I learned about in one of my ecology classes. In human terms, parasitism is like the one cousin (or friend) that always comes to you asking for money and claiming they’ll pay you back but they never do.

Mutualism, commensalism, and parasitism are the main types of symbiosis. There are others that I will probably mention as I talk about the various other species, or if I want to dedicate another post to symbiosis. I know it’s a lot of word vomit, but I hope I made a bit more palatable than standard textbook explanations. Personally, I find symbiotic relationship like parasitism really interesting, especially with parasitoid wasps. I could easily see myself studying the wasps that may have inspired the Xenomorphs from Alien in an alternate universe!

In another alternate universe, I think I’d dedicate my life to researching sloths too. Sloths are maddeningly adorable, I could spend hours watching them. I wish there was a way to watch what my alternate selves were doing with their lives. Wouldn’t that make for some fun reality TV!

A Little Book of Knowledge: Sharks by Bernard Séret

Cover of A little Book of Knowledge: Sharks by Bernard Séret and illustrated by Julien Solé

On Earth Day 2020, I read two books: World Without Fish by Mark Kurlansky with illustrations by Frank Stockton, and A Little Book of Knowledge: Sharks by Bernard Séret and illustrated by Julien Solé. I’ve already talked about the first book, so now let me talk about this little book about sharks.

When it says little, they mean it, with a short forward this book has about 82 pages of content and fits in a small bag. Originally written in French, this book was recently translated to English and they added a forward by David Vandermeulen that explains some of the history behind our current shark hysteria. The translations are pretty good, I almost forgot they weren’t written in English.

Truly an unique read, I don’t think I’ve read anything like this before. Imagine a documentary on sharks where the focus is on a leading French marine biologist roaming around as he speaks. Now, imagine that documentary in the form of a comic book and that’s what this book is. A Little Book of Knowledge: Sharks takes scientific literature and combines it with a graphic novel to create something new.

The illustrations are beautiful! Julien Solé did a wonderful job portraying the sharks with such detail, but not too much to distract from the rest of the book. The coloring is simple, and they depict so many different kinds of sharks and scenarios. Truly, this alone could entertain young children for hours!

Unfortunately, even though it is written like a graphic novel, I believe that children may have a hard time understanding the language of the book. There will probably be some terms and concepts that might even be hard for some adults to get right away. But this in itself isn’t a bad thing because it provides an opportunity for people to learn more on their own. Let me explain.

Something I’ve noticed with the many young people that I’ve encountered over the years is that they know a lot more than you think, especially if they’re crazy about it. I once had a conversation with an 8 year old child who knew more about the wobbegong (an Australian shark) than I did, even knew the scientific name, diet, and relationship with the Aborigines. They were so excited to talk to someone about the shark, especially someone they knew could follow along and talk back to them about it. I tell this story because I see this book sparking similar interests in other children.

I believe that this book can spark the interest of thousands of children with the illustrations alone—they’re absolutely fabulous! Even if the young person doesn’t understand the harder terminology, I believe that the sparked interest will eventually lead them to finding out what they mean on their own and that’s wonderful. Nothing brings me more joy than knowing that someone doesn’t just stop after the first step, that they continue finding out information on their own or with additional help and I believe that’s the purpose of this book.

I recommend it as a gift for any child you think might love sharks. They will enjoy the illustrations, and it’ll give you an excuse to help them learn more things together. I recommend that any parent or older adult reads this book with their kids so that you can share a new found love for sharks, because they are truly amazing creatures. Yes, some of the more complex topics might be hard to understand but hopefully the illustrations will help. In the end, I think it’ll be worth it.