Central Idea

Comb jellies, or ctenophores, are marine animals with jelly-like bodies and iridescent combs.
They represent an ancient animal lineage and have a distinct nervous system.
A recent study published in Science examined the comb jelly nervous system and made surprising discoveries.

What are Comb Jellies?

Comb jellies, also known as ctenophores, are marine animals that belong to the phylum Ctenophora. They are fascinating creatures with a unique and delicate appearance.
Despite their name, comb jellies are not actually true jellyfish.
They have a gelatinous, transparent body that is often luminescent and adorned with rows of cilia, or comb-like structures, which give them their characteristic shimmering appearance.

The researchers aimed to investigate how nerve net neurons in comb jellies connect.
Contrary to expectations, synapses (junctions between neurons) were absent in the nerve net.
Instead, nerve-net neurons were continuously connected by a single plasma membrane.

In the 1950s, electron microscopy confirmed the separate-cell nature of neurons connected by synapses.
Ctenophores challenge this notion by having a syncytial nerve net, as observed in the new study.
Ctenophores attracted attention due to their status as a potential early animal lineage.
Whole-genome sequencing studies supported the theory that ctenophores branched off early in animal evolution.

The evolution of ctenophore nervous systems remains unclear to biologists.
Leonid Moroz proposed a controversial theory of independent nervous system evolution in ctenophores and other animals.
Ctenophores exhibit a unique nervous system lacking classical neurotransmitter pathways and common neuronal genes.
The absence of muscle-based movement and reliance on cilia might have driven the evolution of a different signal conduction system.

Researchers aim to study the development of nerve net neurons in ctenophores.
They seek to determine if adult ctenophores retain syncytial nerve nets or develop synapses.
The uniqueness of ctenophore nervous systems provides valuable insights into the evolution of the nervous system.
Comparative analyses of unique animal systems like ctenophores aid in understanding neuronal function and treating disorders.

Understanding the functional and evolutionary significance of syncytial nerve net neurons in ctenophores requires further research.
This study serves as a crucial foundation for investigating the evolution of nervous systems in animals.
Comparative studies on small marine creatures like ctenophores offer insights into the fundamental principles of brain function.

Ctenophores: Another term for comb jellies, referring to marine animals belonging to the phylum Ctenophora.
Nerve Net: The diffuse nervous system found in comb jellies, composed of interconnected neurons.
Synapses: Junctions between neurons that allow for communication and transmission of signals in most animals, including humans.
Plasma Membrane: The outer membrane of a cell that separates its internal components from the external environment.
Neurotransmitter Pathways: The specific chemical signals used by neurons to communicate with each other in the nervous system.
Syncytial Nerve Net Neurons: Neurons within the nerve net of comb jellies that are interconnected without the presence of synapses.
Colloblasts: Specialized cells in comb jellies used for capturing prey by producing adhesive substances.