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Project Lab 

April 26, 2013

What is an animal?

It may seem like a basic question, but ask someone and listen to the variety of responses that you get and sometimes, a bit of confusion and uncertainty.  This week I’m going to diverge from my recent themes of fieldwork, research and nudibranchs and focus on something a little bit more central to biology.

A couple years ago, I was designing an activity for a lesson plan (see it here).  The activity was based on the game “Guess Who,” but features some classic California coast animals including some fish, sea urchins, and sea anemones.  When it came time to test it out, I asked a (non-biologist) friend of mine to play with me.  Halfway through the game, my friend made a comment about how half of the cards weren’t animals.  WHAT???  I was taken aback, why of course they are ALL animals!   Here is the dialogue that followed,

 

Me: Well, how do you define an animal?

Friend: Something with a face.

Me: Do you consider an insect to be an animal?

Friend: No.

Me: But insects have faces…

At this point, another friend jumped in

Friend2: Oh I know, an animal produces milk, has hair and…

Me: That’s the definition of a mammal!

 

And that seems to be the source of some of this confusion.  Many folks confuse the definition of “animal” with the definition of “mammal,” or sometimes “vertebrate.”  But the reality is that mammals (approximately 5,700 described species) and vertebrates (animals with a backbone, approx. 62,000 described species, including mammals) make up a small minority of the animal life on our planet. The vast majority of the animal life on our planet are invertebrates (animals without a backbone) including insects, spiders, snails, clams, seastars and many animals that your wildest dreams couldn’t imagine (approx. 1.2 million described species, with many more to be discovered).

animals

So what is an animal, then?

First thing’s first.  All of the categories of life that you may hear about are created and defined by humans to better understand the life on our planet.  The categories themselves change as we learn more about the relationships between different living things.  Occasionally, some organisms do not fit neatly into the categories we’ve created, and the following is my attempt to simplify this, so it should be taken with a grain of salt.  If this stuff truly interests you, I encourage you to learn more because the life on our planet is SUPER fascinating stuff!  That’s why I became a biologist in the first place. : )

To be an animal, you must be a living thing and you must be made up of many cells (multicellular). This criterion alone eliminates the bacteria and some other living things called archaea and others called protists.   Oh and by the way, not only must you be multicellular, but you have to be made up of cells that have their insides bound up in membranes (these are called eukaryotic cells).   Bacteria and archaea have cells that lack these internal membranes, and are not multicellular, so they definitely do not fit the definition of an animal.

Animal cell

 

There are some additional requirements to qualify as an animal.  To be an animal, the cells that make you up must form specialized tissues or you must be made up of different types of cells.  You also cannot have a hard structure around your cells called a cell wall.  Multicellular living things that have cell walls made up of a substance called cellulose are what we call plants, and most plants use energy from the sun to create their own food (the process known as photosynthesis).  Animals cannot directly undergo photosynthesis (I know of some sea slug exceptions to this rule!).  Multicellular living things that have cell walls that contain a substance called chitin are what we call fungus (though there are some species of fungus that are single-celled, but let’s not get too complicated today).

Eukaryota_cell_structure plantcap

So the next time you wonder, is that an animal?  You could run through the above requirements (multicellular, cells with no cell wall and cannot make its own food through photosynthesis), though that might seem a bit overwhelming.  Often time if someone asks me if something is an animal, I’ll just ask, well, is it a plant or a fungus? If not, then it’s likely an animal since you can’t see most bacteria or archaea with your naked eye and unless you are looking under a microscope you are unlikely to observe any protists in person.  I will admit that some animals, like corals and sea squirts can be a bit tricky since they don’t move around much, and some folks might mistake them for plants, but the most important thing to remember is that things like insects, corals and worms are animals!

So why does this matter?  I can think of several reasons why this matters, but I will focus on 2 main reasons:

1.  People’s understanding of this directly impacts conservation.  For example, corals are animals and some species of corals are responsible for the beautiful and economically important coral reefs on our planet.  If people do not understand that these are animals, how will we understand the threats they face (pollution, climate change, ocean acidification) and how to protect them?

2. By ignoring the animals that don’t have faces, or don’t have hair, you are missing out on the majority of the animal life living on our planet, and you are missing out on some pretty cool animals that have life histories that are far more interesting than any science fiction I’ve ever read.

So until next time, enjoy one of my favorite invertebrate animals…

Chromodoris_willani2_PR10_PCA73_CASIZ_191052_9224

 

Vanessa Knutson

Project Lab Coordinator and Graduate Student


Filed under: Uncategorized — project_lab @ 10:37 am

April 17, 2013

DEEP SEA MONSTER FOUND BY RESEARCHERS IN CAROLINE ISLANDS WATERS!

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Is this a fantasy, or could it be true? This bogus headline describes a real event that took place in 2005, when Lori Bell and Pat Colin of the Coral Reef Research Foundation were diving off of Palau in the Caroline Islands using the Deep Worker Submarine. While working at depths between five hundred seventy and six hundred seventy feet they encountered and collected 2 specimens of an apparently unknown species of nudibranch.

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Those of you who have been following our Project Lab blog have already been exposed to the wonderful world of nudibranchs. For those who haven’t, nudibranchs are marine slugs that have fascinated divers, tide-poolers and researchers alike with their often fantastic and beautiful appearance and their interesting behaviors.

While the majority of nudibranchs are relatively small, (less than an inch to a couple of inches), this bright-red monster was over four inches long, and sported a veritable forest of branched tentacles (branchial plumes) used to increase surface area for ‘breathing’. Nudibranchs have been collected by divers to a depth of about two hundred fifty feet, and at far greater depths by dredging from boats, but a collection from this depth was very unusual.

The collectors sent the specimens back to California Academy of Sciences to “Nudibranch Central,” the lab of Dr. Terry Gosliner for identification. At that time, I was a Masters student in Terry’s lab, working on the nudibranch family Tritoniidae, of which this beast appeared to be a member. We knew right away that this was a new species, and set about describing it.

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Marionia bathycarolinensis (Smith and Gosliner) was described in 2005 in the Proceedings of the California Academy of Sciences. Very little is known about the life of this animal, but we were able to determine what it was eating by examining stomach contents. With the help of Dr. Gary Williams (Octocoral Research Center at the Academy) we identified an octocoral of the genus Paracis as the sole stomach contents. This was the first record of an association between a nudibranch and this genus of coral. Tritoniid nudibranchs use an oral veil with tentacles to sense their prey, and jaws to grab and bite the coral polyps while the rasp-like radula scrapes away and pulls in tissue. The corals have calcified plates or spicules that must present a problem to digestion, but this family of nudibranchs has a series of hard plates in its muscular stomach (see a. and b. in the photo above) that help grind up the coral skeleton.

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The jaws of this nudibranch were unusual in having a set of rodlets (see photo above) instead of teeth on their chewing edge, and other anatomical features helped differentiate this animal from all others in its family. As far as I know, it hasn’t been observed or collected since.

Until next time,

Vic Smith

Project lab imager and recovering nudibranchaholic.


Filed under: Uncategorized — project_lab @ 10:45 am

April 10, 2013

Specimen of the Day: Brown Creeper

Sometimes I find myself staring up into a tree and losing myself in thought. At times it is productive thought but sometimes I’m just gazing, thinking of nothing in particular. There’s the rare occasion, though, that I’m rewarded by a glimpse of a Brown Creeper making its way up the tree trunk searching for small and tasty insects. Though not an often occurrence, it’s always exciting to watch these small birds as they forage from tree to tree and I get the feeling that many may often overlook these residents of San Francisco.

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The Brown Creeper (Certhia americana) is the only species of treecreeper that occurs in North America – other treecreepers can be found in Europe and parts of Asia. Here in North America, Brown Creepers can be found, as their name indicates, creeping up the trunk of a tree. Starting at the bottom, they have a unique spiraling trek up and around the trunk looking for insects and then when they reach the top they fly to the base of their next trunk. Much like woodpeckers, Brown Creepers have a stiff tail that they use as leverage as they inch their way up. Their brown mottled coloring makes them difficult to see against the bark so you may have to take a second look to find these birds!

I’ve seen these birds at Sutro Heights, Stow Lake and also in Cole Valley, so they aren’t impossible to spot while out and about. One other place to check out these birds is in the research collection at the Academy of Sciences. Since the study skin that I prepared this weekend was found in San Francisco, comparing it to other Brown Creepers found in the City can identify regional differences of the Bay Area population. Within each population of Brown Creepers there can be slight color variations from brown to brownish-red to grey. Using the research collection, scientists can also study these morphological trends over larger geographical regions like North America, even over the last few decades! In the next photo, you can see that some of the specimens in the research collection were found in the late 1800s to early 1900s. Looking at these specimens from over a hundred years ago gives researchers a baseline of historical data to use in their research about how these birds have potentially changed over time. Who wouldn’t want to study these amazing birds?!

brcr_1

Codie Otte

Curatorial Assistant and Specimen Preparator

Ornithology & Mammalogy Department


Filed under: Uncategorized — project_lab @ 11:16 am

April 3, 2013

A Mouse? A Bird? It’s a Mousebird!

Recently, I’ve been preparing some very cool specimens from South Africa. South Africa has a unique array of habitats and an incredible amount of biodiversity, which means that it is home to a wide variety of animal and plant species. There are 858 bird species found there! Here, you can see six different species that I pinned to dry.

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Although all of the different species are equally interesting, one of my favorites is a unique bird called a mousebird. There’s not a lot of recent research published about these birds, so they are an invaluable part of our collection. Historically, mousebirds were found in Europe, but presently are only found in Africa. They are the only species in the family Coliidae as well as the order Coliiformes, and there are only six species total. So, why are they called mousebirds?

31-mar-2013_picture-2

As you can see, they have very long tails and their body feathers are short and fur-like. An even more interesting feature is the fact that they can rotate their first and fourth digits on their feet to effectively grasp on to a variety of surfaces. This allows mousebirds to scurry along the branches of trees, much like a mouse might. Combined with its physical appearance, it’s clear how this bird got its name.

In our research collection, we have specimens of four of the six species of mousebirds, three of which are found in South Africa. The Blue-naped Mousebird, third bird from the left, is found in Eastern Africa. Having these study skins gives researchers the opportunity to learn more about these fascinating birds.

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It’s always a nice change to be able to prepare study skins of birds that aren’t from California. If you ever are lucky enough to travel to Africa, hopefully you’ll catch a glimpse of a mousebird before it scurries away!

Laura Wilkinson

Curatorial Assistant and Specimen Preparator

Ornithology and Mammalogy


Filed under: Uncategorized — project_lab @ 12:30 pm

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