WIP

Been a while since I posted anything, so here are a few pictures of various specimens in the works.

Recently I was lucky to get hold of a shortfin mako (Isurus oxyrinchus) head. It's a small individual, but I was very happy about it since I've been looking for this species for a long time. Since I got it during this year's comparative anatomy practicums, I also used the opportunity to bring it to the lab, which was a lot of fun. I then did the rough part of the cleaning process when the course was over.

Speaking about chondrichthyan jaw suspension.

The cleaned skull during the whitening process.

It's been a while since I macerated anything, but I kind of forgot several specimens in the maceration tanks which are now piling up and waiting to be degreased.

Various mammal and reptile skulls waiting to be degreased.

Still in the fish department, I was also able to get a couple of really cool-but tiny heads. Without the complete body it's hard to be sure but those are probably some kind of barbelled dragonfish (most probably in the genus Stomia). They are not in very good shape and have been kept in ethanol for a while but I'm currently in the process of cleaning the skull, more on that when I'm done with them.

Barbelled dragonfish head (Stomias sp.). Awesome little critter.

I've also been skinning and drying a couple of specimens for beetle work. We have some cool facilities at the lab to dry sediments that turned out to be very useful to dry critters as well.

Blue dot grouper (Cephalopolis taeniops). Found this one at the local fish store and ate it before saving the skeleton. Very tasty, and beautiful fish that should make a nice little skeleton.

Couple of captive bred herps, a python and chameleon. It was the first time I dissected one of these and they have a fantastic anatomy. Really looking forward to work with the skeleton of this one.

And finally, still playing around with clearing and staining specimens. Still have to get better at this, but I recently completed a batch of snakes so thought I would share a pic. Hopefully I will soon have other cool cleared specimens to show. And special thanks to a friend at the lab who gave me a hand skinning all these, and more :)

Cleared and stained cornsnakes (Pantherophis guttatus) and hognoses (Heterodon nasicus).

Half digested baby barracuda skull

Well, maybe not quite exactly, but close. It's certainly partially digested, and I'm quite sure it's a sphyraenid, though it might be difficult to get a more precise ID based on its morphology. This guy was found in the stomach of a nicely sized small-spotted catshark (Scyliorhinus canicula) during last week comparative anatomy practicum. It's always interesting to see students' reactions when offered to investigate stomach contents, some are totally grossed out, but quite a few get really excited about it. We found all sort of things this week, mainly crustaceans, worms and small fish. I remember when I performed this same dissection as an undergrad a few years ago and found a large squid in the stomach of my specimen, a large female. I still have the beak I extracted from the half digested meal and the eggs I removed from the uterus laying around in a jar somewhere.

Partially digested sphyraenid head. Yum.

Catshark breeding

For once this post will not feature too much dead stuff, but there will still be plenty of fish. We've had our own small catshark (Scyliorhinus canicula) breeding facility for a few months now. We currently have 15 mature individuals kept in a large tank at a nearby marine station, where they're happily reproducing and laying plenty of eggs.

The adults. They usually rest on the bottom of the tank but grow quite animated during feeding time.

Curious catsharks.

Plenty of eggs. Embryos are visible through many of them.

We bring the eggs to the lab every week or so, where we keep them in a large aquarium until the reach the desired developmental stage. The nice part is that although the eggcase color will vary from female to female, you can always see through it and check on the developing embryo inside.

Developing embryo.

We keep our weekly harvest in individual baskets in a large aquarium. The sausage shaped things on the bottom are tunicates (Ciona intestinalis). In the lower right corner you can see a newly hatched catshark resting on the bottom of the aquarium.

Catshark embryos at various developmental stages. From left to right: 1.5, 4 and 5 months old.

Scale bars: 0.4/0.6/0.8 cm

Blue-tongued skink skeleton

Some time ago I was asked by a french veterinarian to clean and articulate a complete blue-tongued skink skeleton (Tiliqua scincoides). The specimen had been autopsied, and the ribcage was damaged in the process. It was not in very good condition when I got it, especially the tail which was badly decomposed. For some reason the last caudal vertebrae had turned soft and spongy, and I could not save them, not sure what caused this. Here are a few pictures of the articulation process.

Sorting out the ribs

Almost done.

Finished skeleton

I usually reconstruct the sternal ribs using wire, but in this case I decided against it since most of the sternal region was missing in the first place (interclavicle, sternum, xiphisternum and sternal ribs were mostly destroyed during the autopsy). I did however reconstruct the missing suprascapulae and am rather pleased with how they turned out.

Here are a couple of pictures of the finished skeleton:

Dorsal view

The yellow spot on the hands and feet are remaining ligaments that didn't whiten very well.

Overall a very cool skeleton to work on, looking a bit like a reptilian version of the daschund.

Blue shark skull

This post is a bit overdue since this specimen has been completed for almost a year now, but I still wanted to write a few lines about it. It was my first large shark skull (and one of my first shark skulls for that matter, since I only started experimenting on numerous catshark specimens a few months later), and I made several mistakes in the process which I'll discuss a bit here.

I found this specimen quite unexpectedly while out to buy some food during the summer of 2013. I always check the fish department as well in case they might have anything of interest, and got really excited when I noticed the large shape on the stall. Although it's meat is sold on a regular basis around here (I'm located on the Mediterranean coast) it was the first time I saw the head in a shop, and the guys there were nice enough to give me the head for free.

Blue shark (Prionace glauca) head.

Close up on the snout showing the ampullae of Lorenzini. The medial rostral cartilage is also visible through the skin.

Dissection of the head, with palatoquadrate and right optic capsule exposed.

The first mistake I made with this specimen was to attempt a complete dissection of the head. While it can be done, it often leads to broken structures in the skull, since in some areas the skin is a lot tougher than the cartilage underneath, especially around the rostrum and orbital processes. Doing so, I damaged one of the preorbital processes, which are fairly developed in this species.

The second mistake was to apply too much heat to the jaw which separated at the joints. Fortunately, the teeth didn't fall out, which is also a common occurrence when too much heat is applied. This is why you can't clean shark jaws by boiling them as Quinn is doing in Jaws.

Re-articulation of the jaw joints.

The jaws can be glued back in place, and on large skulls I use wire as well for additional strength. Even then, the jaws will be much more fragile and delicate than if the ligaments are preserved. The palatoquadrate and meckel's cartilage are carefully drilled and wired with brass wire and glued back together. The same process can be used for the hyomandibulars and to glue the jaw to the chondrocranium. On large specimens, I prefer to remove the jaw from the chondrocranium for proper cleaning. This way I can also apply heat to the chondrocranium without damaging the jaws.

Gluing the hyomandibulars back in place on a blacktip reef shark (Carcharhinus melanopterus).

 Another issue with the blue shark is the tendency of the chondrocranium to warp a lot as it dries. Freeze drying might reduce this issue, but every specimens I've been able to see so far displayed a high degree of distortion.

Dorsal view of a blue shark skull, showing important distortion.

Anyway, it was still a very interesting specimen to work on. I hope to get my hands on a second one later one so I can clean it properly without repeating the same mistakes.

The finished specimen. I also kept the ceratohyals and basihyal and might glue them back later.

Catshark skulls and labial cartilages

Labial cartilages are widespread in modern sharks, and they are also found in their relatives: rays, chimaeras and are known in several fossil form. They are paired (up to three pairs) cartilage structures supporting the mouth corners, come in a variety of shapes and sizes and may help with suction feeding in some species.

 Skull of Squatina sp., showing the massive labial cartilages (in green). Source unknown.

Despite some references in the literature (for example Parker's 1876 work), I completely missed them in the first catshark skulls I cleaned. In Scyliorhinus canicula, there is two pairs of thin rod-shaped labial cartilages.

Skull in the cleaning process where labial cartilages have been removed.

Labial cartilages are so thin in this species, it is difficult to keep them in place during cleaning. The best option might be to carefully remove them while taking good reference pictures to be sure to put them back in the right place afterward.

Close up on the upper right labial cartilage.

Couple of finished Scyliorhinus canicula skulls with the labial cartilages in place. Scale bar: 1cm

Next step is to try to preserve the scleral rings for this species, as they are so thin they tend to shrink beyond recognition during the drying process.

References: ParkerW.K., 1876. On the structure and development of the skull in sharks and skates.

Greasy stuff

Grease is a prominent issue when dealing with bones for a variety of reasons : conservation (the grease might turn acidic, which can in turn damage the mineral part of the bone structure. It can also provide a growth media for mold or fungus.), aesthetic (greasy bones are usually yellow or brown, unpleasant to look at and handle), smell (ever smelled a cupboard/room full of greasy whales ?) and so forth. On the other hand some people and museums go light on the degreasing due to a belief that bones that have not been degreased hold together better in the long run. While there might be some truth in this, I think specimens must at least be superficially degreased to avoid to have bones literaly oozing grease. The amount of grease present in a specimen varies depending on a variety of factors: species, season, age, sex, etc.

I'm currently working on a couple of nicely greasy fish, so I figured it would be a nice occasion to illustrate the issue.

Flathead catfish (Pylodictis olivaris)

First one is a partial flathead catfish skeleton, straight out of the beetles (not beetled by myself). It's not overly greasy, but you can still see the various shades of yellow and brown clearly asking for some degreasing.

American eel neurocranium (Anguilla rostrata), occipital view

Here you can clearly see liquid grease oozing from the basioccipital area. This specimen was also beetled. Maceration usually gives a head start on degreasing over beetle cleaning but results in the disarticulation of the specimen.

Mahi mahi (Coryphaena hippurus) neurocranium degreasing

I always use acetone to degrease fish material. It should be handled with care but it works very well for small vertebrates. Other degreasing techniques, especially a prolonged soak in warm water and detergent are more appropriate for larger specimens.