It’s time for #SharkScaleSaturday again! Continuing with the theme of missing denticles, this tail surface of a leopard #shark is missing several. Missing #denticles occur all around the body of all species we’ve looked at so far. #swimming #fishsci #SharkScience

It’s time for #SharkScaleSaturday again! Data on #shark denticle ridge heights are rare since you need 3D imaging to measure. Here's a 3D view of a #bonnethead denticle and ridge profile from work with @mollygabler (scale in um). #fishsci #sharks #SharkScience

It’s time for #SharkScaleSaturday again! This time an image of the Atlantic sharpnose shark skin surface, mid caudal fin. Notice the missing denticles and see if you can find at least 4 denticles in various stages of being replaced from below. #fishsci #sharks #SharkScience

To study the hydrodynamic function of shark skin, we made a flexible airfoil from mako shark skin which we moved with a robotic controller. A leading edge vortex (LEV) forms that is weaker when denticles are removed! #SharkScaleSaturday #fishsci #sharks #SharkScience

To study how shark skin might function, we 3D printed rigid denticles on a flexible membrane (in different configurations), and moved them with a robotic controller. Particles reveal flow patterns! #SharkScaleSaturday #fishsci #sharks #SharkScience

Mako shark skin denticles are relatively small; to visualize them in 3D, high-resolution µCT scans are needed (1.5 to 0.3 µm voxels). Movie of an individual mako denticle shows the expanded crown, neck, and base. #SharkScaleSaturday #fishsci #sharks #SharkScience

Shark fin 3D surfaces vary from leading to trailing edges. For #SharkScaleSaturday, two 3D height maps from leading (left) and trailing (right) dorsal fin areas in smooth dogfish. Blue is low, red high, surface height is from 92 µm to 28 µm. #fishsci #sharks #SharkScience

For #SharkScaleSaturday and #SharkWeek, check out these 3D height maps of the mid-caudal fin (left) and pectoral fin (right) surfaces in smooth dogfish. Blue is low, red high, and the surface heights range from 53 µm to 39 µm respectively. #fishsci #sharks #SharkScience

At the trailing edge of thresher shark tails some denticles are attached to the ceratotrichia which stick out and form the true trailing edge. Lots of missing denticles at this location too! #SharkScaleSaturday #fishsci #sharks #SharkScience

Convergence in skin roughness in the pelagic realm? Dylan Wainwright led our analysis (https://bit.ly/2LsJ2KH mako shark skin (with a replacement denticle coming in) and a table with bony fish and cetaceans for comparison #SharkScaleSaturday #fishsci #sharks #SharkScience

It’s about “missing” denticles for #SharkScaleSaturday. Leopard sharks have relatively few missing but the anal fin surface and the caudal trailing edges reveal some gaps. Images are 3D GelSight images (shown as b&w in 2D). #fishsci #sharkskin #sharks #SharkScience

For #SharkScaleSaturday, a shark scale contribution to recent talk on academic Twitter about low-word-count posters! Here’s an effort from our lab with undergrad first author Madeline … published paper at https://bit.ly/2LLQeRs #fishsci #sharkskin #sharks #SharkScience

Something different for #SharkScaleSaturday today: top and side views of an airfoil completely covered with 3D-printed shark denticles! (see https://bit.ly/2Xh1Vqv Denticles increase lift as well as reduce drag. #fishsci #sharkskin #sharks #SharkScience

Shark tail denticles vary considerably in size and shape from leading to trailing edge. For #SharkScaleSaturday, surface profilometry images comparing denticle shapes on three thresher shark tail regions. Missing denticles are normal! #fishsci #sharkskin #sharks #SharkScience

So many denticles, so little time! Continuing the theme of shark denticle diversity for #SharkScaleSaturday this week, comparison of gulper shark nose tip denticles (left), and mid-lateral body denticles on a leopard shark (right) #fishsci #sharkskin #sharks #SharkScience

Denticles erupting through the epidermis (ouch!) can be seen in the skin of chain catsharks. Look in the center to see pieces of epidermis trapped in notches next to the central denticle spike. Image is 1.2 mm wide. #SharkScaleSaturday #fishsci #sharks #SharkScience

A second tweet for #SharkScaleSaturday to show another nice denticle pattern, this time from a chain catshark. Sample from the skin just anterior to the first gill slit. #fishsci #sharks #SharkScience

Shark skin denticles form beautiful patterns, seen here in a micro-CT scan movie of a patch of leopard shark skin. Visible from underneath … openings into the pulp cavity in each denticle! (Missing denticles are normal) #SharkScaleSaturday #fishsci #sharks #SharkScience

Most published images of shark skin show nearly “perfect” denticles. But zoom out as in this #mako shark image to see damage and “missing” denticles that are being replaced from underneath. It’s natural! Image is 3 mm wide. #SharkScaleSaturday #fishsci #sharks #SharkScience

More on competition swimsuits compared to shark skin for #SharkScaleSaturday! An image of the BlueSeventy suit (smoother than a thresher shark tail), and a table comparing shark mid-tail roughness with three suits. #fishsci #sharkskin #sharks #SharkScience #swimming

Shark scales/denticles are amazingly diverse, in both size and shape! For #SharkScaleSaturday this week, a comparison of denticles from three species shown at the same size: gulper shark, white shark, and smooth dogfish. #fishsci #sharkskin #sharks #SharkScience

Is shark skin anti-fouling? I think not, but others disagree! If samples are not ”overprepared” surface scum and even bacteria are visible on mako denticles. @MarianneEPorter and @hannahherbst07 are working on this too! #SharkScaleSaturday #fishsci #sharkskin #SharkScience

Silky sharks (Carcharhinus falciformis) feel very smooth, but they have typical closely-packed denticles and surface roughness for a pelagic shark. For #SharkScaleSaturday, midlateral body denticles from a silky shark (6.7 by 8.1 mm). #fishsci #sharkskin #sharks #SharkScience

Back to #SharkScaleSaturday after vacation to look inside the denticle of a chain catshark! Cracking open a denticle reveals a very large pulp cavity with remarkable fibrous plywood-like dentine fibers (L to R, 1.2 mm to 15 um wide) . #fishsci #sharkskin #sharks #SharkScience

In most sharks, denticle shape changes gradually around the body. At this location in chain catsharks there is dramatic change within just 3 denticles! Rounded to spiky with sharp ridges. Image is 0.8 mm wide. #SharkScaleSaturday #fishsci #sharkskin #sharks #SharkScience

It’s a new denticle for #SharkScaleSaturday, erupting through the epidermis in Scyliorhinus canicula. Denticles at this location are smooth with low ridges. Looks like a tooth because … it basically is! Image is 0.6 mm wide. #fishsci #sharkskin #sharks #SharkScience

It’s a single large (0.43 mm) denticle for #SharkScaleSaturday! From the small spotted cat shark Scyliorhinus canicula. Beautiful sculpting at the denticle base, and converging ridges to the posterior tip. More to come in future tweets! #fishsci #sharkskin #sharks #SharkScience

For #SharkScaleSaturday, it’s porbeagle (Lamna nasus) time! Image is of skin on the lateral head surface behind the gills. Each denticle has relatively large ridges (note the few “missing” denticles that are being replaced). #fishsci #sharkskin #sharks #SharkScience

High res (0.3 um) uCT scan of thresher shark tail denticles for #SharkScaleSaturday shows a regenerating denticle that never makes it to the surface, but has fully developed ridges. New and developing denticles have large pulp cavities #fishsci #sharkskin #sharks #SharkScience

It’s #SharkScaleSaturday! Denticles around the opening to a mako lateral line canal pore. Note how the denticles spiral in, become smoother and more pointed. How does this pattern affect water flow around the opening … we don’t know! #fishsci #sharkskin #sharks #SharkScience