How is an lancelet different then a fish?

Answer 1

A lancelet is ... The lancelets (subphylum Cephalochordata, traditionally known as amphioxus) are a group of primitive chordates. They are usually found buried in sand in shallow parts of temperate or tropical seas. In Asia, they are harvested commercially for food for humans and domesticated animals. They are an important object of study in zoology as they provide indications about the origins of the vertebrates. Lancelets serve as an intriguing comparison point for tracing how vertebrates have evolved and adapted. Although lancelets split from vertebrates more than 520 million years ago, its genome holds clues about evolution, particularly how vertebrates have employed old genes for new functions.[1] In the issue of Nature on 19 June 2008, the draft genome sequence of the Florida lancelet (Branchiostoma floridae) was reported.[2] -Wikipedia Yes, lancelets are animals, their supphylum is cephalochordata.

Answer 2

Unlike a fish, Lancelets lack the spine that protect the notochord. This places them into the subphylum Cephalochordata. Lancelets share several similarities with fish, however they are none vertebrate chordates.