The culture from planktonic trochophore
stage to semi benthonic pediveliger stage lasted from 14 to 18 days at 25[degrees]C and 12 to 16 days at 29[degrees]C, and lead to the obtaining of 17.2 million of pediveliger larvae (64% survival).
larvae of serpulid annelids sometimes arrest beat of the metatroch while the prototroch beats (Strathmann et al., 1972; Lacalli, 1981, 1984).
In bivalve, the formation of the nervous system occurs early during its ontogenetic development, the appearance of the first neurons that constituting the nerve ganglia occurs in trochophore
larva stage (Croll & Dickinson, 2004).
The transformation of embryos to trochophore
larvae occurred 17.5 h after fertilization, which included the formation of a pear-shaped body, a tuft of cilia in the episphere, and the ciliary ring above the mouth (prototroch), which enabled the larvae to move (Fig.
Most bivalves have a biphasic life cycle that consists of actively swimming planktonic larval stages (from a ciliated trochophore
to a pediveliger larva) and sedentary benthic adult animals (Figure 2).
After 16-18 hours, embryo had differentiated into trochophore
, measuring approximately 45.42- 48.30[micro]m in length.
(free-swimming larva with cilia) and the veliger (second larval stage seen in the diagram above with beginnings of foot, shell, and mantle) bear faint resemblances to their end product, the mature bivalve mollusk that forms the basis of a tasty meal.
Morphological and behavioral defenses of trochophore
larvae of Sabellaria cementarium (Polychaeta) against four planktonic predators.
In many spiralians, the embryo passes through a trochophore
or a trochophore-like larval stage, characterized by a transverse belt of ciliated, trochal cells.
Presence or absence of embryos (including all stages from fertilized eggs to trochophore
larvae) and veliger larvae (including all stages from veliger larvae to juveniles; stages differentiated as described by Kraemer and Galloway, 1986) was recorded for each adult.
At this concentration, around 85% of embryos reached larval D stage while only 16 [+ or -] 21% arrived at the trochophore
stage (the previous stage to larva D).
We could not distinguish embryos from nurse eggs within capsules at the earliest stages, but at the next stages capsules contained non-developing nurse eggs and several embryos at gastrula and trochophore