Related Experiment Video
Updated: Jul 6, 2026
09:15
Processing Embryo, Eggshell, and Fungal Culture for Scanning Electron Microscopy
Published on: August 16, 2019
Fossilized eggs in a pennsylvanian blastoid
Science (New York, N.Y.)
|June 11, 1976
Summary
Fossil blastoids, Pentremites rusticus, from Oklahoma show evidence of brooding. Abnormal anal hydrospires in this echinoderm species likely housed eggs, suggesting a reproductive adaptation.
Area of Science:
- Paleontology
- Marine Biology
- Evolutionary Biology
Background:
- Pentremites rusticus is an extinct echinoderm from the Early Pennsylvanian period.
- Sexual dimorphism is known in some blastoid species.
- Hydrospires in blastoids are typically associated with respiration.
Purpose of the Study:
- To investigate an unusual finding in a Pentremites rusticus specimen.
- To determine the function of abnormal anal hydrospires in this fossil.
Main Methods:
- Microscopic examination of a fossil specimen of Pentremites rusticus.
- Analysis of abnormal hydrospire structures within the specimen.
Main Results:
- Hundreds of apparent eggs were observed within the abnormal anal hydrospire group of the specimen.
- The hydrospire structure appeared modified for egg retention rather than respiration.
Conclusions:
- The abnormal anal hydrospires in this female Pentremites rusticus specimen likely served as a brooding structure for eggs.
- This finding suggests a reproductive strategy involving modified hydrospires in this sexually dimorphic blastoid species.
Related Concept Videos
01:38Fertilization
During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ovary, and travels into the fallopian tubes. The process requires several key steps: 1) sperm present in the genital tract must locate the egg; 2) once there, sperm need to release enzymes to help them burrow through the protective zona pellucida of the egg; and 3) the membranes of a single sperm cell and egg must fuse, with the sperm...
01:33Cleavage and Blastulation
After a large-single-celled zygote is produced via fertilization, the process of cleavage occurs while zygotes travel through the uterine tube. Cleavage is a mitotic cell division that does not result in growth. With each round of successive cell division, daughter cells get increasingly smaller.
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...