In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The tests included open - field exploratory behaviour , elevated plus maze and elevated zero maze , social interaction and novelty - suppressed feeding latency behaviour .
### Output Text:
The tests included open - field exploratory behaviour , elevated plus maze and elevated zero maze , social interaction and novelty - suppressed feeding latency behaviour . 