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Strongylocentrotus purpuratus

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The purple sea urchin, known scientifically as Strongylocentrotus purpuratus, is a vital marine invertebrate.

Strongylocentrotus purpuratus (3108600644)
Strongylocentrotus purpuratus (3108600644)

It belongs to the family Strongylocentrotidae. These animals live along the eastern edge of the Pacific Ocean. Their range extends from Ensenada, Mexico, to British Columbia, Canada. They occupy lower intertidal and nearshore subtidal communities. This species is more than just a colorful resident of the ocean. It serves as a critical model organism for scientists studying cell and developmental biology.

Physically, the purple sea urchin is defined by its deep purple color. Its body is protected by a hard exoskeleton called a test. These urchins reach sexual maturity at approximately two years of age. Their reproductive cycle is seasonal, with active months typically occurring in January, February, and March. During this time, they secrete orange eggs into the water. While they grow to a specific diameter, they are remarkably long-lived. Some individuals can live for as long as 70 years. They also possess a unique ability to regenerate damaged or aging tissue.

In the ocean, these urchins are key members of the kelp forest community. They live alongside other species like sea otters and abalones.

Strongylocentrotus purpuratus (3108600644)
Strongylocentrotus purpuratus (3108600644)

The balance of this ecosystem depends on predators. For example, sea otters are a main predator of the urchin. When sea otter populations declined, the urchin population boomed. This growth can threaten the health of kelp forests. If urchins eliminate all the kelp in an area, they create an urchin barren. This process is currently occurring due to the effects of climate change.

Scientists have turned to the purple sea urchin to unlock the secrets of genetics. In 2006, large teams from over 70 institutions sequenced its genome.

Strongylocentrotus purpuratus (3108600644)
Strongylocentrotus purpuratus (3108600644)

This included the Kerckhoff Marine Laboratory and the Baylor College of Medicine. This was the first echinoderm genome to be completely sequenced and annotated. The genome is estimated to encode about 23,500 genes. It is largely non-redundant, which makes it very comparable to vertebrates. This makes the urchin an excellent tool for studying complex biological systems.

The genome reveals fascinating evolutionary connections. Sea urchins are the closest living relatives to chordates, the group including humans.

Strongylocentrotus purpuratus (3108600644)
Strongylocentrotus purpuratus (3108600644)

Using strict measures, humans and purple sea urchins share 7,700 genes. The urchin genome contains 353 protein kinases. This includes members of 97% of human kinase subfamilies. Scientists found that many genes once thought to be unique to vertebrates actually exist in the urchin. These genes help the urchin sense its environment, despite the animal lacking a head. They also possess a chemical defensome to eliminate toxic chemicals during stress.

Research into the urchin genome has direct implications for human medicine. Many urchin genes are orthologs, or similar counterparts, to genes associated with human diseases.

Strongylocentrotus purpuratus (3108600644)
Strongylocentrotus purpuratus (3108600644)

For example, they have genes related to Reelin, which is linked to lissencephaly syndrome. They also share proteins with the Usher syndrome network, such as usherin and VLGR1. In 2012, researchers at the University of St Andrews studied a specific viral region in the genome. They found a sequence that might return cells to a stem-cell-like state. This research could eventually help with treatments for cancer and Alzheimer's disease.

Environmental changes also impact the biology of these organisms. Increasing concentrations of carbon dioxide in the ocean affect the urchin's epigenome. This means the environment can change how their genes are expressed.

Strongylocentrotus purpuratus (3108600644)
Strongylocentrotus purpuratus (3108600644)

Higher carbon dioxide levels also reduce the size of their larvae. This reduction may negatively impact the overall fitness of the species. Understanding these connections helps scientists study the broader relationship between climate change and marine life. The purple sea urchin remains a vital link between marine ecology and human biomedical progress.

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