Blastoid

Associated Smithsonian Expert: Kathy Hollis, M.S.

Kathy Hollis with Triceratops obtusus, collected in 1890 by John Bell Hatcher

Courtesy of Adrienne Block

Kathy Hollis is the collections manager in the Smithsonian National Museum of Natural History Department of Paleobiology. As a kid she would give rocks as gifts, assuming everyone thought rocks were as cool as she did. She majored in geology at the College of Wooster in Ohio and went on to finish a master’s in geology at the Ohio State University in 2005. It was at Ohio State that Kathy realized her love for museum collections. She finished a master’s in Museum Studies at the University of Colorado at Boulder in 2008 specializing in collections care and museum-based research. Kathy has been at the Smithsonian since 2010 and helps to care for one of the largest fossil collections in the world. Her work involves getting the information about what organisms lived when and where out of the collection drawers and making it digital, accessible, and searchable online. Kathy brakes for fossil echinoderms.

Meet our associated expert

This image was obtained from the Smithsonian Institution. The image or its contents may be protected by international copyright laws.
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  • This image was obtained from the Smithsonian Institution. The image or its contents may be protected by international copyright laws.
  • This image was obtained from the Smithsonian Institution. The image or its contents may be protected by international copyright laws.
Scientific Name
Pentremites americana
Catalog Number
55183
Number of objects in this
record: 4
Discipline
Paleobiology
Time Period
Paleozoic
Carboniferous
Collecting Locality
North America, United States, Kentucky
Precise Locality
Rte. 421
Upper Level Taxonomy
Animalia, Echinodermata, Blastoidea, Spiraculata, Pentremitidae
Region
US Southeast (NC, SC, GA, FL, AL, MS, TN, KY)
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Side view of fossil blastoid (Heteroschisma alternatum)
Photo by Smithsonian Institution, Department of Paleobiology
  • Side view of fossil blastoid (Heteroschisma alternatum)
    Photo by Smithsonian Institution, Department of Paleobiology
  • Fossil blastoid (Pentremites godoni) showing holes for respiration
    Photo by Smithsonian Institution, Department of Paleobiology

About Blastoids (Class Blastoidea): Paleobiology

Blastoids (sometimes called sea buds for their shape) have a long stalk with a head at the top. They went extinct about 260 million years ago (during the Permian), but they used to be abundant on Earth. Their heyday was during the Mississipian (about 350 million years ago). They lived anchored to rocks by their stalks, feeding by filtering small food from seawater. At the top of their head is a mouth, surrounded by grooves with tiny hairs for trapping food. The structure of their stalks and heads is what left a record of their existence. The stalk is made of stacked, calcified disks. The head is made of rows of tightly interlocking, calcified plates that often remain together in the fossil record. A set of holes in the top of head are evidence of the blastoid's unusual respiratory system. Folded structures (hydrospires) were used to extract oxygen from seawater that passed through the holes.

Related Resources

Smithsonian Research on Paleobiology

The U.C. Museum of Paleontology's Introduction to Blastoids

Blastoids described by the University of Bristol

Fossil echinoderm (Geocome sp) from the Jurassic period
Photo by Smithsonian Institution, Department of Paleobiology
  • Fossil echinoderm (Geocome sp) from the Jurassic period
    Photo by Smithsonian Institution, Department of Paleobiology
  • Fossil echinoderm (Anartiocystis foerstei) showing attachment stalk
    Photo by Smithsonian Institution, Department of Paleobiology
  • Fossil starfish (Urasterella asperula)
    Photo by Chip Clark, Smithsonian Institution

About Echinoderms (Phylum Echinodermata): Paleobiology

Echinoderms appear in the fossil record more than 500 million years ago, during the early Cambrian. What are usually left behind are hard mouthparts or parts of their skeletons, made of calcite plates. Rarely, an entire skeleton fossilizes, for example in a situation where it was quickly buried in sand. Even a piece of skeleton can provide information, because echinoderms have specific patterns in their skeletons. The echinoderms you see today have five-point (pentaradial) symmetry, often noticeable in five arms. While some of the earliest echinoderms were pentaradial, others had unusual body shapes. The “helioplacoids” had long, oval-shaped bodies with no arms, and a spiral pattern on the surface from tube feet wrapped around a central core. Helioplacoids went extinct even before the end of the Cambrian, as did a variety of other echinoderms, including the star-shaped Somasteroidea. Some echinoderms survived and diversified, becoming dominant in the oceans of the Paleozoic era.

Related Resources

Explore Echinoderms at the Encyclopedia of Life

Learn About Echinoderms on the Animal Diversity Web

See what the Tree of Life says about Echinoderms