Like other members of the order Myliobatiformes, the mobuloids have broad, well-developed pectoral fins, in certain species, a stinging spine, and a whip-like tail. Unlike the others, the devil rays have large cephalic lobes which create mobile peribuccal fins which direct food into the mouth. These are the largest batoids, reaching widths of twenty feet and weights of 3,000 pounds, according to Bigelow & Schroeder.

These rays use their wing-like pectoral fins to work near surface waters, feeding on small pelagic organisms -- schooling fish and planktonic crustaceans. They have no need for the grinding dentition of other representatives of the order. This is reflected by the numerous small, and often very poorly developed, teeth of recent species. In Manta, and certain species of Mobula, i.e., M. japanica, the teeth are peg-like. In Manta, however, teeth are only present in the lower jaw.

In general, the mobulids represent small to very large rays of subtropical and tropical waters. They are planktonic feeders that often school. Although single-cusped teeth are usually bilobate, they have polyaulacorhizous roots which are most evident in those teeth which are mesio-distally elongated.

Fig.1 Mobula hypostoma Lesser devil ray

Western Atlantic Devil Rays

The Bigelow & Schroeder (1948) inventory of rays from the western North Atlantic included: Mobula hypostoma RAFINESQUE, 1810 , possibly the eastern Atlantic species M. mobular (BONNATERRE, 1788), Ceratobatis robertsii BOULENGER, 1897, and Manta birostris (DONNDORFF, 1798).

Notarbartolo di Sciara (1987) did an extensive revisionary study of the genus Mobula and concluded that there were nine extant species. He found teeth to be quite variable in the genus, and placed greater significance in soft tissue morphological delimiters, such as the branchial filter plates and body pore placement, none of which are likely to appear in the fossil record. Candidates for Lee Creek include those listed by Bigelow & Schroeder (C. robertsii deemed synonymous with M. hypostoma) and several species that are known from the eastern Atlantic: M. rochebrunei (VAILLANT, 1879), M. thurstoni (LLOYD, 1908), M. kuhlii (VALENCIENNES in Müller & Henle, 1841), and M. tarapacana (PHILIPPI, 1892). Unlike most studies of living batoids employed in this research, this work provides excellent detail of tooth morphology.

Mobula hypostoma - (BANCROFT, 1931) Lesser devil ray

This is a small (up to four feet in width) ray of subtropical and tropical coastal waters of the western Atlantic, from Argentina to North Carolina, including the Caribbean and Gulf of Mexico. Notarbartolo di Sciara describes it as having no caudal spine and smooth-crowned imbricated teeth which display strong sexual dimorphism. He points out that the male teeth generally have two cusps, and that single and triple cusped teeth are less frequent.

The female dentition is made up of low-crowned teeth (fig. 4). The illustrated partial dentition (USNM #232,731) has 53 upper and 48 lower files. The upper teeth range from 1.5 to 3.0 mm in width, larger in the mesial and distal positions. The lower teeth are more widely separated, unlike the closely packed upper teeth.

The male dentition is made up of teeth with elongated cusps (figure 3). The specimen used for the illustration (fig. 2, USNM #232,732%) had 56 upper files, which measure 62 mm wide by 7 mm deep. The teeth range from 1.5 to 3.0 mm in width, with the larger teeth usually in mesial and distal positions.

Fig. 2 M. hypostoma USNM #232,732, male dentition 16.4 cm in width

H. hypostoma upper medial files, USNM #232,731 & 2, Labial at bottom Fig. 3 (left) Male. 1st LH, symph, 1 thru 7 RH files; Illustrated width = 10.0 mm. Fig. 4 (right) Female. 1 thru 6 LH, symph, 1st RH; Illustrated width = 9.5 mm.