actinula


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actinula

[ak′tin·yə·lə]
(invertebrate zoology)
A larval stage of some hydrozoans that has tentacles and a mouth; attaches and develops into a hydroid in some species, or metamorphoses into a medusa.
References in periodicals archive ?
A polyp released from 20 to 300 actinula larvae, depending on the degree of maturation.
The resulting structure contrasts with the well-developed cushion-like tissue in the endoderm of the aboral half of an actinula larva and the absence of digestive gland cells in the endoderm of the oral half of the larval body (Fig.
22-[micro]m-FSW), some actinula larvae remained floating or repeated temporary attachment for more than 2 weeks.
Several researchers preliminarily reported on the settlement behavior of actinula larvae of Tubularia spp.
We found that actinula larvae attached temporarily to the substrata by AI discharge, and that the function of the larval tentacles changed irreversibly--from temporary attachment to feeding (and defense)--after larval settlement.
Whereas Berrill (1952) and Hawes (1958) concluded that actinulae of Tubularia are merely juvenile polyps and not really "true" larvae, the present study clearly shows that the actinula larvae of T.
In addition, we demonstrated that actinula settlement was promoted by direct contact with microbial films formed on the substrata surface, and that settlement-delayed larvae retained many Ms in their aboral tentacles.
This report, which reveals that nematocyte-printing behavior is an active metamorphic event and that nematocyte dynamics is synchronously involved in the attachment and morphogenesis of actinula larvae, provides new insights into the attachment and morphogenesis of cnidarian larvae.
Preliminary observations on the settlement of actinula larvae of Tubularia larynx (Ellis and Solander).
Actinula larvae showed a pattern of greater abundance over invertebrate-covered than over algal crust-covered areas.
Ascidian tadpole larvae, actinula hydroid larvae, and mussel pediveligers all showed a pattern of greater abundance 1-5 cm from the vertical rock surfaces (Table 6).