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Project Lab 

September 26, 2012

Dermestid Domain

Two weeks ago in our Project Lab blog, Laura spoke about masceration and briefly touched on the role dermestid beetles play in skeletonizing specimens for the O&M department. Working with the beetles is one of my favorite aspects of my job here at the Academy and I thought I would go into a bit more detail regarding our wonderful, interesting dermestid colony!

dermestid case

Dermestid beetles (family Dermestidae) are a large group of scavenger beetles that feed on a variety of organic materials from hair to skin to dead flesh. Dermestids can be found on carcasses almost anywhere in the world! Taxidermists and scientific preparators have long used these beetles to help quickly and efficiently clean bones of flesh because the beetles do most of the work for us! Out in the O&M Bones Lab, we use a colony of Dermestes maculatus, a small black beetle with a white ventral side, to help prepare skeletons for the research collection.

dermestes-maculatus-wcap

Dermestids are perfect for terrarium life as the right hand “man” of the preparator. Although capable of flight, our Dermestes maculatus don’t take to wing unless they get too hot, so we keep our terrarium case pleasantly warm to keep the beetles happy just strolling around. This makes opening and closing their case much easier and prevents beetles from escaping and munching on other specimens. They also require little care aside from feeding and the occasional spritz of water. The work they do for our department vastly outweighs their salary (all paid in food!).

The first step in skeletonizing a specimen is to remove most of the flesh off the animal, leaving only a small amount of muscle on the bones. Up in the Project Lab, you can find O&M staff and volunteers regularly skeletonizing specimens for our research collection. Once the muscle has been removed, it is time for the dermestid colony to begin their work.

lepus-californicus-with-larvae

A large colony will be able to strip a small bird clean in just a few days! Dermestid beetles are excellent for cleaning small, delicate skeletons like fragile passerine birds and tiny mammals, and also juvenile species whose bones have not yet fused. Sometimes with water masceration (as described by Laura in her previous post), skeletons can fall apart from being submerged in liquid for long periods of time. In contrast, the dermestid beetles will eat the flesh off the bones and generally keep the skeleton articulated and this can be preferable for some specimens to prevent important sutures from falling apart.

lepus-californicus-clean

Once cleaned by the dermestids, the skeleton will be brightened and degreased and then integrated into our collection, ready to be used by a curious researcher… maybe you!

Codie Otte
Curatorial Assistant and Specimen Preparator
Ornithology & Mammalogy Department


Filed under: Uncategorized — project_lab @ 4:27 pm

September 21, 2012

DNA and its Importance to Taxonomy

Taxonomy entails the description, naming, and classification of living things. Why is taxonomy so important? Well, it helps us categorize organisms so we can more easily communicate biological information. Taxonomy uses hierarchical classification as a way to help scientists understand and organize the diversity of life on our planet. Hierarchical classification basically means that we classify groups within larger groups.

The basic hierarchy of classification is described below for the sea slugs I study in the Project Lab. This listing is an oversimplification of hierarchical classification since there are categories between those shown.  The hierarchical names of organisms reflect the general physical attributes of the organisms placed within these groupings.   For example, all of the animals within the Mollusca share the feature of being soft-bodied.

doto-classification

You may have heard of scientific names before, and perhaps you noticed that they contain two parts. Scientific names of organisms include the genus followed by the species name.  An example of a species within the sea slug family I am researching is Doto ussi Taxonomy is important since other scientific disciplines like conservation and drug discovery hinge on organisms being classified and named.

Prior to being able to sequence DNA, organisms were described and categorized solely by their distinct morphologies (physical characteristics) and ecological roles.  The ability to sequence DNA has revealed a great deal more about where an organism belongs taxonomically and helps pinpoint new species.  DNA is now used alongside morphology and ecology to substantiate an organism’s distinctiveness in the biological world.

Doto sp. 9

A component of my graduate project is looking at the DNA of Doto sea slugs of two different morphologies from the Indo-Pacific. These morphologies include specimens with a short body and elongate body from Indonesia, Papua New Guinea, and the Philippines. Prior to in-depth study, these elongate individuals were placed within the sea slug family Dotidae, despite their unique appearance.

Doto sp. 14

DNA sequences from these individuals will be compared to those of the short bodied to determine if these elongate specimens should in fact stay within the Dotidae. We do not really know where these specimens belong taxonomically, since they are new to science. This is very exciting since a new genus or family may need to be created to accommodate these individuals. It is discoveries like this that make science so rewarding and fun! DNA has truly changed how we do science and has made the classification of organisms more concrete.

Carissa Shipman

Masters Student

Invertebrate Zoology & Geology Department


Filed under: Uncategorized — project_lab @ 10:52 am

September 12, 2012

Dem Bones

Do you know how many bones a bird has? What about a cat? A shrew?

Honestly, neither do I. It would be rather painstaking to count each bone, especially since it varies among species. All I know is that there are a LOT!

If you’ve been by the Project Lab, you’ve likely seen myself or Codie (or maybe one of our wonderful volunteers) working on preparing study skins. Have you ever wondered what we do when we want to keep the skeletons of these animals?

Bones Lab

Depending on the condition of the specimen and the rarity of the species, we can either choose to make both a study skin and what is called a “partial skeleton,” or a full skeleton. Study skins still have a few bones left in them for structure (feet in mammals and skull, wings, legs and feet in birds), so if we want to keep both the skin and a skeleton, the skeleton wouldn’t be complete. If a specimen comes to us too damaged to make a nice skin, we can strip away as much of the meat as possible and keep just the bones. From there, we do one of two things in order to clean off all of the muscle: macerate it or give it to our colony of dermestid beetles.

Maceration is the process of rotting the tissue off of the bones in water. Sound disgusting? It absolutely is, but it does the trick! We simply place the body of the animal, with as much muscle removed as possible, in a container filled with warm water and let it soak for a couple of weeks. After a few series of rinses with clean water, we have a beautiful skeleton! You can see a clean skeleton going through its last soak here:

final soak

Admittedly, the cooler way to clean these skeletons is with our dermestid beetle colony. These are flesh-eating beetles that, luckily for us, only feed on dead flesh. We don’t have to worry about them munching on us when we add carcasses to their tanks! A few weeks with the beetles and our skeletons come out nice and clean. Here are two rodent skeletons that are almost ready to be taken out from the dermestids:

rodent bones

Both maceration and our beetle colony allow us to prepare skeletons without the use of harsh chemicals that may damage the bone over time. Now “dem bones” are clean and will remain in our collection for hundreds of years!

Laura Wilson

Curatorial Assistant

Department of Ornithology & Mammalogy


Filed under: Uncategorized — project_lab @ 12:24 pm

September 6, 2012

Sea Slugs 101

I recently started working in the Project Lab here at the California Academy of Sciences and one of my favorite aspects of working in here is sharing my research with museum visitors. Many visitors do not realize that the Academy is a place of active scientific research. We have researchers studying everything from viruses to plants to spiders and everything in between, including some enigmatic creatures that you may have never even heard of before… sea slugs.

cephalaspidean-richard-lingcc

I can’t quite pinpoint how or when I first learned about sea slugs— it may have been an IMAX movie, or it may have resulted from having a dive buddy who was an underwater photographer and sea slug junkie. Whatever it was, little did I know that my fate was tied to these amazing animals.

Today I find myself in a master’s program working on sea slugs, and my research project fills most of my days and many of my nights and dreams as well. I realize that not everyone knows what sea slugs are, so I’d like to do a little bit of explaining.

If you remember back to biology class, you may remember a group of animals known as mollusks (phylum Mollusca). Mollusks are soft-bodied, and include animals such as squid, snails, and clams. Sea slugs are a group of mollusks that live primarily in marine habitats and are slug-like, hence the name. They are slug-like because through the course of evolution, many groups of these animals have reduced or lost their shells in the adult stage.

nudibranchs are seaslugs

Within the sea slugs (for the record, we call these opisthobranchs in the scientific community), there is a group that is particularly interesting to me— the nudibranchs. Nudibranch literally means “naked gill.” Nudibranchs have no trace of a shell in the adult stage, so their gills are “naked” or exposed on their backs, unprotected by a shell. The nudibranchs have evolved all sorts of interesting ways of protecting themselves from predators. Many species have hijacked defense mechanisms from their prey. For example, many aeolid nudibranchs feed on cnidarians, animals that have stinging cells such as corals and jellies, and are able to use these stinging cells for their own protection.

gymnodoris-aurita-

Sea slugs can be found from the shallow intertidal to the deep sea, and from the polar regions to the tropics. I encourage you to look for sea slugs and particularly nudibranchs the next time you find yourself tidepooling. Though, I will warn you that there are some sea slug imposters out there. Some folks occasionally refer to sea cucumbers as sea slugs (a real challenge with common names compared to scientific names, but that is a whole blog post of its own).  Sea cucumbers are not mollusks. They belong to a different phylum, or group of animals, known as the Echinodermata, or echinoderms. This group includes seastars, sea urchins and other animals that have five-part radial symmetry as adults. To confuse things even further, there are species of sea cucumbers that in their juvenile stage look exactly like nudibranchs!

sea cucumbers

In general, most sea cucumbers that you may encounter tend to be a lot larger than nudibranchs and other sea slugs.  Most sea slugs that I have run across are about 3 inches in length or less, whereas most sea cucumbers I have encountered are much larger than this.  If you happen to see tube feet (elongated sucker-like structures like what you would find on the bottom of a seastar), you know that you’ve got a sea cucumber instead of a sea slug (though not all sea cucumbers have tube feet).  Another indicator would be to look for rhinophores.  Rhinophores are the two sensory structures on the head end of a sea slug. Not all sea slugs have these, but if you see them, you probably have a sea slug.

rhinophores and gills

I will leave you by saying that sea cucumbers are not the only sea slug imposters out there, but I’ll save the others for another time.

Vanessa Knutson

Project Lab Coordinator and Graduate Student

Invertebrate Zoology and Geology


Filed under: Uncategorized — project_lab @ 3:46 pm

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