Males have also been observed eating benthic-dwelling elasmobranchs (Condit and Le Boeuf 1984) and are known to prey on cyclostomes, a behavior that is rare in females (Antonelis et al.
Males may forage opportunistically on these prey while in transit but their principal prey appear to be benthic animals located along the continental margin, possibly elasmobranchs and cyclostomes.
An unusually large cyclostome
bryozoan (Pennipora anomalopora) from the Upper Cretaceous of Maastricht.
The competition between the two clades has, however, been stable over the last 100 million years (McKinney, 1995a); that is, cheilostomes have consistently overgrown cyclostomes in two-thirds of their encounters (mean 0.
I have used both the original data and that from Barnes and Dick (2000) to address three questions: (1) What characteristics of cyclostomes allow them to persist alongside cheilostomes?
The mean numbers of cyclostomes and cheilostomes were standardized to recruits per 30-day period, and these values were graphed against time; standard error bars were generated with data from the monthly, three-panel replicates.
The outcomes of interference competition between cyclostomes and cheilostomes were recorded on panels at three sites at Lough Hyne and at various depths: Rapids, 3 m; Rapids, 6 m; Whirlpool, 6 m; Whirlpool, 12 m; Labhra, 6 m; and Labhra, 12 m.
The proportion of recruits that were cyclostomes was, in contrast, considerably higher (especially outside summer periods) and more variable.
Histochemical distribution of peroxidase in amphioxus and cyclostomes
with special reference to the endostyle.
Earlier studies of cyclostomes largely employed fractured and polished or etched sections and provided only limited information.
Despite Carter and Clark's assignment of the fabrics described in cyclostomes by Ross (1977) to semi-nacre, the first well-supported claim of semi-nacre in cyclostomes was made by Taylor and Jones (1993) for Hornera robusta and H.
In these free-walled cyclostomes (suborder Rectangulata) there is a gradation between the granular fabric and a succeeding foliated fabric of elongate crystallites that are distally oriented and imbricated.
With further investigation of fossil and Recent cyclostomes it should be possible to evaluate this and other skeletal ultrastructures as phylogenetic characters.
The lamprey, which is a cyclostome, has spermatozoa that carry a spherical acrosomal vesicle at the anterior end of their heads, subacrosomal material between the acrosome and the nucleus, and a long perforatorium rod through the nucleus (Follenius, 1965; Stanley, 1967; Nicander and Sjoden, 1971; Jaana and Yamamoto, 1981) [ILLUSTRATION FOR FIGURE 6B OMITTED].
Reproduction in cyclostome fishes and its regulation.