Based on the reference provided, the question "What fish has no spine?" is not entirely accurate because it implies a complete absence of any skeletal support. While true fish do have spines (backbones), some fish-like creatures have alternative support structures. A better question would be "What fish-like creatures lack a true backbone (spine)?"
The answer is lancelets, lampreys, and hagfish lack a true backbone (spine). They are supported by a jelly-like rod, which is a precursor to a true backbone.
Here's a more detailed look:
| Creature | Backbone? | Support Structure | Description |
|---|---|---|---|
| Lancelets | No | Jelly-like rod (notochord) | Small, eel-like marine animals. |
| Lampreys | No | Jelly-like rod (notochord) | Look like eels; use circular mouths to rasp flesh. |
| Hagfish | No | Jelly-like rod (notochord) | Eel-shaped; produce slime as a defense mechanism. |
| True Fish | Yes | Backbone (spine) | Possess a vertebral column made of bone or cartilage. |
Lampreys are particularly interesting. As the reference states, they "look like eels" and "bite their prey with their circular mouths, rasping away the flesh and sucking the blood and tissue." This parasitic feeding behavior is facilitated by their lack of a bony jaw, which is characteristic of jawless fish.
Therefore, while true fish possess a spine, the statement above identifies certain fish-like creatures, specifically lancelets, lampreys, and hagfish, that lack a true backbone but have a supporting structure.
