The life cycle of an echinoderm
Pluteus larva of a sea biscuit
Larva with six arms.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, dark field, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Growth of antero-lateral pair of arms (2nd pair).
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, larva, planktonic, planktotrophic, polarized light
Pluteus larva of a sea biscuit
Larva with six arms.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Pair of coeloms developing next to the gut in a two-arm larva.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, larva, planktonic, planktotrophic, polarized light

Pluteus larva of a sea biscuit
Larva with two pairs of aarms and early development of postero-dorsal arms on the body sides.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Larva with six arms.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, dark field, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, larva, planktonic, planktotrophic, polarized light
Pluteus larva of a sea biscuit
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, dark field, larva, planktonic, planktotrophic

Pluteus larva of a sea biscuit
Stage with three pairs of arms and vestibule invagination on the left side.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Coelomic sacs in a two-arm pluteus larva.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Pluteus larva of a sea biscuit
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, larva, planktonic, planktotrophic
Embryo before the second division
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 16 cells
Micromere positioning at the vegetal pole.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 16 cells
View of the animal pole.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 8 cells
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 108 cells
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 4 cells
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Ectodermic cells during blastula formation
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Second cell division
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo during blastula formation
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 16 cells
Lateral view showing the position of micromeres.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 2 cells
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Second cell division
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 32 cells
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 1 cell
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo during blastula formation
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 8 cells
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Embryo with 32 cells
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
First cleavage
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo
Juvenile sea biscuit
Aboral surface (opposite to mouth).
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, juvenile, polarized light
Juvenile sea biscuit
Ambulacral feet and spines.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, Differential interference contrast, juvenile
Juvenile sea biscuit
Oral region.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, Differential interference contrast, juvenile

Juvenile sea biscuit after metamorphosis
Ossicles of the lantern of Aristotle in formation at the oral region.
Size: tiny
Place: São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, juvenile, polarized light
Juvenile sea biscuit
Ossicles of the lantern of Aristotle in formation at the oral region.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, juvenile, polarized light
Juvenile sea biscuit
Anus on the juvenile aboral surface (red curved structure).
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, Differential interference contrast, juvenile
Juvenile sea biscuit after metamorphosis
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, dark field, juvenile
Juvenile sea biscuit
Oral region with the lantern of Aristotle in formation.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, juvenile, polarized light
Juvenile sea biscuit
Aboral region (normal position).
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, dark field, juvenile
Juvenile sea biscuit
Lantern of Aristotle in the oral region.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, juvenile, polarized light
Calcareous spicule
Skeleton being secreted by primary mesenchymal cells.
Size: micro
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: <0.1 mm, Differential interference contrast, embryo, planktonic
Archenteron of prism larva
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo, larva, planktonic
Gastrula
Archenteron during invagination.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo, planktonic

Sea biscuit metamorphosis
Regression of larval tissues. Spicules of the larval skeleton are still present in the aboral region.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, Differential interference contrast, juvenile, larva, metamorphosis

Sea biscuit metamorphosis
Polarized light highlights the calcareous skeleton showing the structure of spines, podia, and remnants of the larval skeleton.
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, benthic, juvenile, larva, metamorphosis, polarized light
Ovules
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, gamete
Sperm
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, gamete
Sea biscuit gamete release (spawning)
Adult specimen releasing sperm in the laboratory.
Size: huge
Place: São Sebastião, SP, Brazil
Tags: >100 mm, adult, benthic, macrophotography
Blastula during hatching
Size: tiny
Place: CEBIMar, São Sebastião, SP, Brazil
Tags: 0.1 - 1.0 mm, Differential interference contrast, embryo, planktonic
In this tour you can follow the life stages of the sea biscuit Clypeaster subdepressus. This echinoderm is related to sea urchins, but its body is flattened and it lives semi-buried in sand beds.
Embryos and larvae were raised in the laboratory at CEBIMar and photographed until they become juveniles. To accomplish that we collected adults from São Sebastião Channel (São Sebastião, SP, Brasil) and induced the release of gametes (ova and sperm). We conducted an in vitro fertilization and documented embryo development under light microscopy.
After a few hours of cell divisions embryos became swimming larvae (pluteus), approximately 0.2 mm wide, which were fed with microalgae until metamorphosis. Inside the larva a small sea biscuit begins to grow. When the first podia and spines are formed the larva sinks to the bottom and goes through metamorphosis. The juvenile sea biscuit reabsorbs the larval tissues and begins to explore the new habitat between sand grains.
Fact sheet
- Number of images: 51
- Creation date: June 15, 2011, 12:07 p.m.
- Last updated: Sept. 22, 2019, 2:54 p.m.
- Contained taxa: Clypeaster subdepressus
- Contained tags: 0.1 - 1.0 mm, <0.1 mm, >100 mm, adult, benthic, dark field, Differential interference contrast, embryo, gamete, juvenile, larva, macrophotography, metamorphosis, planktonic, planktotrophic, polarized light