Here is the passage:
Marina, the beautiful mermaid, wanted some tuna
salad. But had a small problem since
she was allergic to celery. At Sammy’s Sub Shop, Marina hoped to find tuna
salad free of this dangerous vegetable. Flopping across the tiled floor
to the counter. Marina placed her order and then checked her sandwich for
celery. Not noticing, however, the spoiled mayonnaise. At five o'clock that
evening, Marina became violently ill with food poisoning. When a lifeguard
at the beach discovered the problem, he called 911. Even though the mermaid
had fishy breath. A handsome paramedic gave her mouth-to-mouth resuscitation.
Wailing like a sick dog, the ambulance sped off to the hospital. Where the
doctor on call refused to treat a sea creature with a scaly tail. A kind
nurse, however, had more sympathy. After she found some Pepto-Bismol. Marina
drank the entire bottle of pink liquid, feeling an immediate improvement.
The mermaid told the rude doctor never to swim in the ocean. For she would
order hungry sharks to bite off the doctor's legs. While sharp-clawed crabs
plucked out his eyes. Tossing her long hair, Marina thanked the nurse for
the Pepto-Bismol. And took a mint from David, the handsome paramedic.
A complete sentence must have a main clause. A main clause will follow this pattern:
Subject + verb = complete thought.
In the highlighted item, Marina is the subject, and wanted is the verb. This pair makes a complete thought, so you do have a sentence.