After 24 h, ciliated blastulae
had thickened vegetal plates (Fig.
This difference arose because neonate sizes were comparable between treatments, but blastulae
from low-scope females were 21% larger than those from high-scope females.
Brisaster latifrons has evolved at least two other characteristics associated with the evolution of nonfeeding larval development: large sperm heads and wrinkled blastulae
. Raff et al.
tenuis at 10-13[degrees]C Event Time Fertilization 0 First polar body 30 min First cleavage 2 h 15 min Second cleavage 3 h Third cleavage 3 h 45 min Ciliogenesis 15 h Swimming blastulae
16 h Gastrulation ~24 h Episphere eyespots ~42-48 h Feeding ~70-75 h Telotroch ~16 d First accessory eyespot ~24-30 d Chaetae ~24-30 d Metamorphosis ~35 d After the onset of feeding at 70-75 h, development rate varies substantially among cultures; times recorded are for rapidly developing cultures.
Though we did not notice any instances in which two embryos developed within the same fertilization envelope, our observations of relatively large distances between the cells of developing embryos, our inability to see a hyaline layer, and our finding that embryos that were irregularly shaped after fourth cleavage later formed regular blastulae
certainly concur with those of Mortensen (1938) and Schroeder (1981).
After 3-4 d, embryos developed into round blastulae
, and after 5 d they started to become triangular.
In the data shown in Figure 1B for 5-day-old blastulae
, 36.5% of ribosomes were present in the polysome fraction.
Passing through the same cleavage stages as in other indirect-developing species, Temnopleurus embryos formed blastulae
at about 6-7 h after fertilization (Fig.
This pattern of accelerated development continued 22 h after fertilization when 42% of the blastulae
at 31.5 [degrees]C had started to invaginate; this process was not observed at 28 [degrees]C until 27 h after fertilization (P = 0.001).
" childressi mussels could be consistently induced via serotonin injection by placing multiple individuals of both sexes together in one container after injection; however, using mussels that were collected in November 2003, we successfully produced a small culture that developed to the hatched blastulae
stage by inducing mussels individually and obtaining sperm and eggs separately.
Patterns in early embryonic motility: effects of size and environmental temperature on vertical velocities of sinking and swimming echinoid blastulae
They found four general patterns of predation: (1) crustacean species ate primarily early embryonic stages, (2) chaetognaths and amphipods ate primarily blastulae
and prism larvae, (3) fish species ate plutei and unhatched embryos, and (4) ctenophore species ate few, if any, prey.
3d, 4e); however, divisions were not always synchronous, resulting in blastulae
with irregular numbers of cells (Figs.
Regarding possible side effects of this inhibitor, anisomycin at 10 [micro]mol [l.sup.-1] did not decrease rates of [.sup.14.C]-alanine transport by blastulae
, gastrulae, and larvae (Table 1).
are highly wrinkled; late blastulae
appear to be smoother.