Porifera & Cnidaria
This kingdom and phylum consists entirely of sessile, benthic, primary consumers that filter feed by pulling water through specialized canals into their internal cavity.
What are Kingdom Parazoa and Phylum Porifera (sponges)?
This filamentous, soft-tissued organ is shared by both brachiopods and bryozoans to maximize surface area and water movement for filter feeding.
What is a lophophore?
Mollusks easily build their hard shells out of these two specific forms of calcium carbonate, utilizing carbon dioxide dissolved in aquatic environments.
What are calcite and aragonite?
According to the provided phylogenetic tree, the clade Bilateria splits directly into these two major animal lineages.
What are Deuterostomia and Protostomia?
Slugs contain internal shells that serve as examples of these evolutionary remnants—body parts or organs that have lost most or all of their original ancestral function.
What are vestigial structures?
These are the three distinct structural body plans of sponges, progressing from thin walls with a single central cavity to a highly complex tertiary structure of folded, clustered walls.
What are ascon, sycon, and leucon?
Unlike clams, which possess bilateral symmetry running between their two shells, brachiopods display bilateral symmetry in this specific physical orientation.
What is down the middle of the front-facing angle, passing directly through both valves?
This predatory class of mollusks possesses a well-developed nervous system and advanced senses, and includes the ammonites that went extinct at the end of the Cretaceous.
What is Cephalopoda?
Based on the evolutionary tree, the Protostomia lineage is divided into Ecdyzozoa and this sister clade, which contains Mollusca, Annelida, Brachiopoda, Bryozoa, Rotifera, and Platyhelminthes.
What is Lophotrochozoa?
This group of mollusks, known commonly as chitons, utilizes an eight-part segmented shell to herbivorously graze on rock algae.
What is Polyplacophora?
This class of active marine predators within the phylum Cnidaria is known commonly as box jellyfish.
What is Cubozoa?
When analyzing brachiopod shell anatomy, these are the respective technical names given to the ventral valve and the dorsal valve.
What are the pedicle valve (ventral) and the brachial valve (dorsal)?
This anatomical process occurs during the early life stage of Gastropods and involves the twisting of the body into a spiral.
What is torsion?
This specific geological boundary is defined by a major biological replacement in which ancient Paleozoic reef builders like Rugosa and Tabulata corals were replaced by modern Scleractinia corals.
What is the Permo-Triassic (P-T) boundary?
Computer modeling software reveals that all living and fossil mollusks combined occupy only a very small percentage of this total theoretical geometry.
What is morphospace?
In the cnidarian life cycle, this is the name of the larval stage that results from fertilization before settling to grow into a polyp.
What is a planula?
This specific, paraphyletic group of inarticulate brachiopods possesses flexible, thin, chitinous shells with simple muscle-held hinges containing organic phosphate materials.
What is Lingulata?
Discovered as a soft-tissued fossil from the Precambrian, this organism is studied as a potential early representative of the phylum Mollusca.
What is Kimberella?
During the Mesozoic Marine Revolution (MMR), macroscopic invertebrates developed these two major protective ecological strategies to defend against rising predation.
What are robust armor and deep infaunal life modes?
These microscopic, chitinous tooth plates belonging to polychaete annelids puzzled paleontologists for years until an exceptional soft-bodied fossil revealed their true location in place.
What are scolecodonts?
These specialized cells within a sponge's body plan are responsible for secreting the tiny, needle-like skeletal structures made of silica or calcium carbonate known as spicules.
What are sclerocytes?
While the bryozoan group Gymnolaemata highly diversified during the Cenozoic, most members of this specific bryozoan group failed to survive past the Paleozoic era.
What is Stenolaemata?
Lacking torsion entirely, this straight-shelled group resembles only one half of a bivalve and provides a model for what ancestral mollusks most likely looked like.
What is Monoplacophora?
This phylum of soft-bodied, nutrient-recycling deposit feeders contains extant worms and serves as the direct evolutionary sister group to the Mollusca.
What is Annelida?
Unlike articulate brachiopods with tooth-and-socket hinges, this specific type of inarticulate brachiopod reproduces a sessile lifestyle by cementing its shell directly to hard substrates.
What is a craniad?