What Is ITIS and How Do You Look Up a Species' Scientific Name and TSN?
ITIS (the Integrated Taxonomic Information System, itis.gov) is a public database of authoritative scientific and common names and their taxonomic relationships, covering all seven kingdoms of life — Archaea, Bacteria, Protozoa, Chromista, Fungi, Plantae, and Animalia — with a focus on North America and global coverage. You use it to confirm the correct spelling and current status of a name, find the accepted name behind a synonym, and get a stable identifier (a TSN) you can cite or link to. It is the right tool when you need a citable name reference or a machine-readable taxonomy; it is not a source for specimen records, images, or geographic occurrences.
What ITIS is and what it covers
ITIS assembles names and their taxonomic relationships in partnership with specialists worldwide and distributes that data openly. It is made up of 11 active Memorandum of Understanding partners and is an Associate Participant of the Global Biodiversity Information Facility (GBIF), as well as a partner and contributor to the Catalogue of Life (COL) and ChecklistBank, which form the basis of the GBIF Backbone Taxonomy.
Two practical consequences follow from that:
- Names are curated, not crowd-sourced. Records reflect specialist review, so a name's presence or absence carries weight.
- The data is designed to be reused. ITIS publishes web services and full database downloads, not just web pages.
The database is large and actively maintained. As of the site's most recent load figures, ITIS reported roughly 1,000,636 scientific names (any rank, any usage) and 167,526 common names, with new and edited names added continuously.
How to look up a name or TSN
The home page offers a quick search with a single input box and a set of filters.
Input: a name or a TSN. You choose the search type from these options:
- Any Name or TSN
- Common Name
- Scientific Name
- TSN
You can also restrict the search to a kingdom — Animal, Plant, Fungal, Bacteria, Protozoa, Chromista, or Archaea — or leave it at "in every Kingdom."
Match behavior: the search supports several matching modes, including exactly, for, containing, starting with, and ending with. Use exactly when you already have a correctly spelled name and want to avoid near-matches; use containing when you only remember part of a name.
Action: enter the term, pick the search type and match mode, and run the search.
Expected result: a results list of matching taxa. Selecting a record opens its full report, which shows the name, its taxonomic placement, and its TSN.
One practical constraint: the site states that its search functionality requires JavaScript, so enable JavaScript or use a JavaScript-enabled browser. If you cannot, the site points you to Advanced Search and Report as an alternative route.
What a TSN is and when to use it
A TSN is a Taxonomic Serial Number — a stable numeric identifier assigned to a taxon in ITIS. The site addresses "What is an ITIS TSN?" directly in its FAQ, and the quick search accepts a TSN as a search type, which tells you the intended use: a TSN is a lookup key.
Use a TSN when you need to refer to a taxon unambiguously:
- In databases and datasets, where a number survives name changes and spelling variants that a text name would not.
- In citations and links, so a reader lands on the exact record you used.
- When reconciling sources, because two sources may use different names for the same taxon but can be matched through the identifier.
A TSN identifies a taxon in ITIS; it is not a global biodiversity identifier used by every system, so do not assume it will match identifiers from unrelated databases.
Beyond quick search: the other ITIS tools
The site groups its data access under Data Access and Tools. The main options:
| Tool | What it does | Use it when |
|---|---|---|
| Advanced Search and Report | Search with more control than the quick search | You need to narrow results or build a report |
| Hierarchical Report | Shows a taxon's position in the classification hierarchy | You need the full lineage, not just the name |
| Compare Names | Compares names across records | You are checking whether two names refer to the same or different taxa |
| Web Services | Programmatic access to ITIS data | You are building a client or automating lookups |
| Full Database Download | Bulk data in database files or TWB format | You need the whole dataset locally |
For programmatic use, the site documents Web Service Information, a Description of ITIS Web Services, guidance on Developing a Client, and ITIS Solr Web Services with Solr WS Examples. For bulk use, it provides Full Database Download Instructions, Database Files, and the option to Download Data in TWB Format. The site also has a route to Become a Data Partner and Contribute, using the Taxonomic Workbench.
Choose the route by volume: a handful of lookups belongs in the web interface; anything repeated or large-scale belongs in the web services or a download.
Citing and linking to ITIS
ITIS treats citation and linking as first-class questions — both "How Do I Cite ITIS?" and "How Do I Link to ITIS?" appear in its FAQ. If you publish work that depends on an ITIS name or TSN, follow the site's own citation guidance rather than inventing a format, and use its linking guidance when you point readers to a record. The site's footer also carries a "How to cite ITIS" link and a privacy statement and disclaimers page.
Common sticking points
- JavaScript disabled. Quick search will not run; use Advanced Search and Report instead.
- Wrong match mode. Searching a partial name with exactly returns nothing. Switch to containing or starting with.
- Kingdom filter too narrow. A name you expect under Animalia may be filed elsewhere, or the filter may exclude the record you want. Try "in every Kingdom" first.
- Expecting occurrence data. ITIS holds names and classifications. For specimen and observation records, you need a different kind of resource.
- Treating a name as fixed. Names and classifications are revised; the site reports new and edited names on an ongoing basis, so re-check rather than assuming a name you recorded earlier is still current.