Modifications of the dorsal fin (Fig. 2-15) include the sucking disc atop the head of the remoras ( Echeneidae ) that allows them to cling to sharks or to other large fishes and be carried along along as hitchhikers. The lures of anglerfishes (Lophiiformes) are modified dorsal spines. A few species involve a showy dorsal in displays for a variety of social purposes.