Giant goblin sharks

 

The two largest goblin sharks ever caught, both 5-6 meter females from the Gulf of Mexico, from Parsons et al. (2002) and Driggers et al. (2014) respectively.

The goblin shark Mitsukurina owstoni was once thought to be a mid-sized shark, and for many years the maximum documented length was 3.84 m (12.6 ft)¹ (Stevens & Paxton, 1985). However, two individuals caught in the Gulf of Mexico in the 2000’s radically changed this idea. They revealed that goblins can attain giant sizes and are actually the third longest lamniform, just ahead of smalltooth sand tigers but behind great whites and basking sharks. The first individual was a female captured from a depth of 919-1,099 m (3,105-3,605 ft) in the northern Gulf in 2000 (Parsons et al. 2002). Although it was not properly measured, its length was estimated from the fishing rope in the photographs. Based on the calculated distance from the eye to the end of the snout, it was determined to be between 5.4 m (17.7 ft) and 6.17 m (20.2 ft) long.

Size chart comparing the largest goblin shark individuals. The goblin silhouette is redrawn from Ebert & Mostarda (2015).

The second individual was another female captured from a depth of 490 m (1,608 ft) and later released in the southeastern Gulf in 2014 (Driggers et al. 2014). Since it was released, it was also not measured and the length again had to be estimated from fishing rope in the photos. Based on the calculated length of the pelvic fins, it was determined to be between 4.86 m (15.9 ft) and 6.35 m (20.8 ft) long. So far, these two are the only specimens recovered from the Gulf of Mexico. It has been suggested that the giant size is unique to this population, but whether they represent a distinct species or subspecies is unknown without DNA analyses. Sexual dimorphism is a more likely explanation for the difference in size from the previous record-holder (which was male). As was the case for smalltooth sand tigers, and other lamniforms in general, females can probably grow significantly larger than males.

Size chart comparing very large and very small individuals of Scapanorhynchus raphiodon.

There are even longer goblin sharks known from the fossil record. The largest specimen I found is a Scapanorhynchus raphiodon anterior tooth (NMMNH P-37728) from the Late Cretaceous Canyon Crevasse Formation of New Mexico (Johnson & Lucas, 2003). No measurements were given in the text, but based on the scalebar in the figure the crown height is roughly 5 cm (2 in). I scaled it assuming that it is the tallest tooth in the jaws, the second lower anterior, and using the regression equation from Shimada & Siegel (2005)². This results in an estimated length of 7.54 m (24.7 ft), longer than the largest recorded great white. Of course, this estimate relies on the scalebar being correct and S. raphiodon having the same proportions as M. owstoni. To show ontogenetic growth, I added a juvenile S. raphiodon (FHSM VP-13961) with an estimated length of only 59 cm (1.9 ft) (Hamm & Shimada, 2002).

Notes

¹All the lengths in this post are total length, measured from the snout to the upper caudal lobe in natural position.
²-93.164 + 16.948 (a2 CH [in mm]) = TL [in cm]

References

• Driggers, W.B., III, Davis, K.S., Moore, C., & Carlson, J.K. (2014). New record of a goblin shark Mitsukurina owstoni (Lamniformes: Mitsukurinidae) in the western North Atlantic Ocean. Marine Biodiversity Records, 7: e96. 
• Ebert, D.A., & Mostarda, E. (2015). Identification Guide to the Deep-Sea Cartilaginous Fishes of the Southeastern Atlantic Ocean. Food and Agriculture Organization of the United Nations.
• Hamm, S.A., & Shimada, K. (2002). Associated tooth set of the Late Cretaceous lamniform shark, Scapanorhynchus raphiodon (Mitsukurinidae), from the Niobrara Chalk of western Kansas. Transactions of the Kansas Academy of Science, 105(1-2), 18-26.
• Johnson, S.C., & Lucas, S.G. (2003). Selachian fauna from the Upper Cretaceous Dalton Sandstone, middle Rio Puerco Valley, New Mexico. In S.G. Lucas, S.C. Semken, W. Berglof, & D. Ulmer-Scholle (Eds.) Geology of the Zuni Plateau (pp. 353-358). New Mexico Geological Society.
• Parsons, G.R., Ingram, G.W., Jr., & Havard, R. (2002). First record of the goblin shark Mitsukurina owstoni, Jordan (family Mitsukurinidae) in the Gulf of Mexico. Southeastern Naturalist, 1(2), 189-192.
• Shimada, K., & Siegel, J.A. (2005). The relationship between the tooth size and total body length in the goblin shark, Mitsukurina owstoni (Lamniformes: Mitsukurinidae). Journal of Fossil Research, 38(1), 49-56.
• Stevens, J.D., & Paxton, J.R. (1985). A new record of the goblin shark, Mitsukurina owstoni (family Mitsukurinidae), from eastern Australia. Proceedings of the Linnean Society of New South Wales, 108(1), 37-45.