Squatina argentina by DOTkamina

Ballpoint pen and brown and black marker illustration of Squatina argentina (Argentine angelshark), dorsal view almost lateral. This representation is very schematic and artistic, and does not necessarily represent the animal's true colors. I also include the other photo with the two previous sketches I made. For this drawing, I based it on photographs by Kriss Shephard (2008), NOAA, and Gadig O.B.F. (FishBase); and on the illustration available at Fish Commercial.

You can find this image hosted on: Wikimedia Commons, Twitter, Tumblr, Threads, Pinterest, DeviantArt, Pixiv, Instagram, Piapro, Bluesky, Behance.

The skecthes!:

Some facts about Squatina argentina.

Attention. I wrote almost none of the following information. It's a combination of various pieces of information that weren't taken from Wikipedia. Sources at the end!

Description: This species is distinguished from its congeners by having a darker background color, ranging from dark-brown to reddish-brown (vs. light-brown to dark-brown in S. guggenheim and S. occulta), with higher number of tooth rows with 24 vertical tooth rows in both upper and lower jaws, tooth formula 12-12/12-12; (vs. 9-9 to 10-10/9-9 to 11-11 in S. occulta, and 9-9 to 11-11/9-9 to 11-11 in S. guggenheim), and with anterior half of pectoral fin margin convex (vs. anterior margin of pectoral fin straight).

Cross section: angular.

Image credit: NOAA.

Distinguishing Characteristics. Differs from S. guggenheim and S. occulta with the interspiracular surface covered by small and homogeneous dorsal denticles, without enlarged denticles (vs. a pair of enlarged, conical and morphologically distinct dermal denticles between spiracles in S. occulta and S. guggenheim); differs from S. occulta by lacking blackish irregular small spots surrounding white spots on dorsal surface (i.e. absence of ocelli-like markings); differs further from S. guggenheim by having the dorsal midline denticles on trunk morphologically similar to other trunk denticles and barely organized in a row (vs. dorsal midline row of enlarged denticles morphologically distinct from other trunk denticles), the denticles close to origin of pectoral fin morphologically homogeneous, similar to other pectoral denticles (vs. presence of a pair, or more, enlarged and morphologically distinct denticles from other pectoral denticles, in S. guggenheim).

Coloration. It varies, but it generally has a sandy brown or brownish-gray body with lighter spots or blotches, allowing it to blend into the sandy or muddy bottom. This camouflage helps it remain hidden from both prey and potential predators.

Dentition. Tooth formula 12-12/12-12.

Biology: Found on the continental shelf and slope. Benthic. It feeds primarily on a variety of bony fishes and smaller bottom-dwelling invertebrates. They can bury themselves in the sand or mud of the seabed, effectively camouflaging themselves and remaining virtually invisible, a phenomenon known as "cryptic behavior." Only their eyes and spiracles (the openings behind the eyes that they use for breathing) remain exposed. 

Parasites: Pontobdella moorei Oka, 1910 (Hirudinea).

Reproduction: Ovoviviparous, embryos feed solely on yolk. Both ovaries are functional. Argentine angelsharks reach sexual maturity at about 120 cm (3.94 ft) in length. The female's reproductive cycle lasts two to three years. The number of pups per litter can vary, but is generally between 9 and 10 (the range is from 7 to 11). When it's time to give birth, the female angelshark releases her already formed pups into the water. The pups are relatively large compared to other shark species, measuring between 30 and 40 centimeters (12 and 16 inches) in length. This size advantage at birth may increase their chances of survival. The Argentine angelshark’s reproductive cycle is thought to be biannual.

Development: After birth, young angelsharks embark on an independent life. They grow and develop through a continuous growth process, shedding their skin and developing new dermal denticles as they grow in size. Angelsharks' growth rate is influenced by factors such as prey availability, environmental conditions, and individual genetics.

Longevity: Not well documented, but it is estimated that they can live at least 15.5 years.

Habitat: It's commonly found in coastal areas, close to the shore, but is also common in offshore waters. They are also associated with estuaries, and the continental shelf and slope, where they find suitable prey and shelter. It prefers sandy or muddy substrates, where it can effectively camouflage itself among the seafloor sediments.  They have also been seen, additionally, in habitats such as sandbanks, seagrass meadows, rocky bottoms, and areas with underwater canyons or reefs.

Importance to humans: The primary threat to Argentine angelsharks is overutilization by commercial fisheries, particularly the trawl and bottom gillnet fisheries in Brazil, where the species is likely most concentrated. The species is reported as a significant bycatch species in the commercial monkfish fishery, which likely contributed to a significant decline in the population in the early 2000s.

Size: 100 to 120 cm. In males: 100 cm, max. 170 cm. Pups: 30 -  40 cm.

Depth: 51 / 100 to 400 m.

Distribution: Southwest Atlantic: Brazil to southern Uruguay, including Argentina.

IUCN status: Critically Endangered (CR) (A2bd). Date assessed: 05 August 2017

References and sources:

• FishBase s.f. Squatina argentina (Marini, 1930). Argentine angelshark.
• MarineBio. 2025. Tiburones ángel argentinos, Squatina argentina. Vida marina.
• NOAA. 30/10/2023. Argentine Angelshark. NOAA Fisheries.
• Squatina argentina at IUCN database. 2017.
• Shark References. 2025. Squatina argentina (Marini, 1930). Argentine angelshark.

Carcharhinus isodon by DOTkamina.

Drawing of Carcharhinus isodon, made with a rapidograph and markers. For this work, I used photographs from the Smithsonian Tropical Research Institute and Bryan Huerta as references. The colors used are purely artistic, they do not represent the actual color of this animal! The image quality probably isn't the best. I'm sorry my camera isn't the greatest. I don't think I'll ever move forward (or have the desire) to make a digital version. I feel better drawing "by hand" away from any screen, I'll always repeat that.

You can find this image hosted on: Wikimedia Commons, Twitter, Tumblr, Threads, Pinterest, DeviantArt, Pixiv.

Some facts about Carcharhinus isodon.

Attention. I wrote almost none of the following information. It's a combination of various pieces of information that weren't taken from Wikipedia. Sources at the end!

Description: Blue-grey on top, greyish on sides, white below, white band on sides, fins unmarked. Body relatively slender; eyes large, round, nictitating eyelids present; snout pointed, length before mouth < mouth width, ~1.1-1.3 time width between nostrils; anterior nasal flaps very reduced; upper lip furrows short, not very noticeable; top and bottom teeth nearly symmetrical, with non-oblique narrow points, lower teeth smooth, upper teeth weakly and irregularly serrated; 12-16 rows of teeth on side of top jaw; spiracle absent; gill slits very long (3rd slit longest, > height of anal fin), last two over pectoral, no papillae; first dorsal relatively small, front margin a little convex, rear margin concave, its origin over or just behind free rear tip of pectoral fin; second dorsal relatively large, with slightly concave rear margin, its origin over or slightly behind that of the anal fin; anal fin with deeply notched rear margin; pectoral fins small, narrow, with angular front edge; no ridge on top of body between dorsal fins; no keel on tail base; tail fin strongly asymmetrical, with well developed lower lobe, undulating ridge along dorsal surface of top lobe, and a notch under tip of that lobe.

Image credit: FAO.

Distinguishing Characteristics

1. Snout pointed, shorter than the width of the mouth.
2. Fins unmarked, the undersides of the pectoral fins are pure white.
3. First dorsal fin originates behind the insertion point of pectoral fins along inner margin.

Small in size with a long pointed snout and fairly large eyes. The mouth is broadly rounded in the front with well-defined labial furrows around the corner of the mouth. The gill slits are very long, about half the length of the base of the first dorsal fin. The origin of the first dorsal fin is over or just slightly posterior to the insertions of the pectoral fins. The first dorsal fin is small with a short rear tip. The trailing edge of the first dorsal is falcate with a rounded apex. The second dorsal fin is moderately large with a short rear tip. The pectoral fins are small. Pelvic fins have narrowly rounded tips. The upper edge of the caudal fin is just about straight with a narrowly rounded tip. There is no interdorsal ridge on the finetooth shark.

Species appearing similar to the finetooth shark include the lemon shark (Negaprion brevirostris), blacktip shark(Carcharhinus limbatus), and spinner shark (Carcharhinus brevipinna). The lemon shark can be distinguished by its second dorsal fin that is almost as large as its first dorsal. The blacktip shark and spinner shark have black-tipped fins while the finetooth shark lacks any distinguishing markings on the fins.

Coloration. This shark is dark bluish-grey or bronze above, paling to grayish then to a white underside. There is an inconspicuous white band along the flank. There are no distinguishing marks on the fins.

Dentition. This shark is named for its very small, clear, fine teeth. The upper teeth are narrow and weakly serrated or smooth with erect to slightly oblique cusps. The lower teeth are erect with smooth cusps and transverse roots. Dermal denticles are small and overlapping. Each is a bit broader than long with blades containing three ridges, each with three short teeth with the median tooth longest.

Biology: Commonly found close inshore. Forms large schools. Feeds on small bony fishes and cephalopods. Distinct pairing with embrace. Viviparous (with a yolk-sac placenta), 1 - 6 to 13 young per litter. The embryos are nourished through a placental connection. Gestation is approximately 12 months with the females moving into nursery areas in late May. Birth occurs from late May to mid-June.

Typically hovering around 10 m (33 ft) deep, the deepest they go is 152 m (490 ft). Adults and juveniles are common in shallow coastal waters off South Carolina during the warm summer months and migrate south when surface water temperatures drop below 20 °C (68 °F). This population of ringtooth sharks winters in waters off the coast of Florida. These sharks are often found near estuaries, lagoons, bays, and off river mouths, as long as the salinity is within their range.

Predators: Larger sharks, including the dusky shark (Carcharhinus obscurus).

Parasites: The parasite Phoreiobothrium triloculatum is known to sometimes inhabit finetooth sharks. This parasite also can affect other related sharks in the Carcharhinus genus. It is found in the spiral valves of the sharks.

Importance to humans: In the western Atlantic, this shark may be incidental by-catch on floating longlines in inshore waters but is considered to have little overall economic importance to the commercial shark fishery. However, local fishermen may target them with gillnets close to shore. In the northern Gulf of Mexico, they are taken occasionally by rod and reel, and the meat is presumably marketed and eaten either fresh or dried-salted. While this shark is not involved in any reported injuries, care should be taken when handling these sharks.

Size: average 129 cm, range 119-139 cm; max 160-200 cm. Size at birth 51 to 64 cm.

Depth: 0-20 to 40 m.

Distribution: Western Atlantic: North Carolina, USA to Cuba, the Gulf of Mexico, and southern Brazil to Uruguay. Occurrence in the eastern Atlantic, specifically in Senegal and Guinea-Bissau have not been confirmed, and may be based on Carcharhinus brevipinna.

IUCN status: Near Threatened (NT) (A2bd). Date assessed: 01 July 2019.

References and sources:

• Carcharhinus isodon at IUCN database. 2019.
• FishBase s.f. Carcharhinus isodon (Valenciennes, 1839). Finetooth shark.
• Raimundo D & Bowling Tyler. 2020. Finetooth Shark. Prepared by: Cathleen Bester. Florida Museum. 
• Shark References s.f. Carcharhinus isodon (Valenciennes in Müller & Henle, 1839). Finetooth shark.
• Smithsonian Tropical Research Institute. 2024. Species: Carcharhinus isodon, Finetooth Shark. Shorefishes of the Greater Caribbean online information system.