Simple and complex burrow morphology in two Macrophthalmus species on the intertidal mudflats of Barr Al Hikman, Sultanate of Oman Author Bom, Roeland A. Author Ebbinge, Maaike text Journal of Natural History 2022 2022-07-11 56 5 - 8 475 485 http://dx.doi.org/10.1080/00222933.2022.2093679 journal article 126745 10.1080/00222933.2022.2093679 c5000e55-78e0-4247-a89e-09f0903e2cba 1464-5262 7012408 Macrophthalmus depressus The casted burrows of M. depressus were complex, with multiple entrances and branches ( Figures 2 and 3 ). In fact, we never managed to make a complete cast of an entire burrow as the tunnels always continued after where the plaster stopped. One burrow appeared to have five entrances and another had two entrances (the 10 burrow entrances into which plaster was poured ultimately proved to belong to five burrows). Branches were observed leading in every direction and tunnels had various slopes and angles. The maximum depth of a cast was 35 cm , at which the water level was reached. In two casted burrows a single crab was found. In the three other burrows the crabs were probably able to escape, as the burrows were more extensive than our casts. The 16 excavated burrows were similarly complex as the casted burrows. In six of the 16 excavated burrows more than one crab per burrow was encountered (up to four crabs per burrow; Figure 4 ). In total 27 crabs were captured, of which we identified seven as males and eight as females. Sex could not be convincingly determined in 12 smaller individuals. There was no relationship between burrow size at entrance and crab size (t = 1.109, P = 0.28, R2 = 0.01; Figure 4 ).