Lesson plan
Tusk shell
Scaphopoda ( ; ) is a class of shelled marine molluscs (invertebrates within the phylum Mollusca), whose members are known as scaphopods ( ) and commonly called tusk shells or tooth shells. They have a worldwide distribution and are the only class of exclusively infaunal marine molluscs. Shells of species within this class range in length , with Fissidentalium metivieri being the longest. Members of the order Dentaliida tend to be larger than those of the order Gadilida. These molluscs live in soft substrates offshore (usually not intertidally). Because of this subtidal habitat and the small size of most species, many beachcombers are unfamiliar with them; their shells are not as common or as easily visible in the beach drift as the shells of sea snails and clams. Molecular data suggest that the scaphopods are a sister group to the cephalopods, although higher-level molluscan phylogeny remains unresolved.
Article summary
Scaphopoda ( ; ) is a class of shelled marine molluscs (invertebrates within the phylum Mollusca), whose members are known as scaphopods ( ) and commonly called tusk shells or tooth shells. They have a worldwide distribution and are the only class of exclusively infaunal marine molluscs. Shells of species within this class range in length , with Fissidentalium metivieri being the longest. Members of the order Dentaliida tend to be larger than those of the order Gadilida. These molluscs live in soft substrates offshore (usually not intertidally). Because of this subtidal habitat and the small size of most species, many beachcombers are unfamiliar with them; their shells are not as common or as easily visible in the beach drift as the shells of sea snails and clams. Molecular data suggest that the scaphopods are a sister group to the cephalopods, although higher-level molluscan phylogeny remains unresolved.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.