Final answer:
About 1.5 million eukaryote species have been described, which is less than 20% of the estimated total of 8.7 million eukaryotic species. The number of prokaryotic species is even greater and largely unstudied. Biodiversity and the ongoing rate of extinction make cataloging all species a challenging task.
Step-by-step explanation:
The number of currently described species on the planet is estimated to be about 1.5 million species for eukaryotes that have been identified, named, and studied. However, it's important to note that this accounts for less than 20 percent of the total number of eukaryote species present on Earth. Scientists have made an estimate that there might be around 8.7 million eukaryotic species in total. Furthermore, there may be an even greater number of prokaryotic species, which are largely unstudied and uncatalogued. Biodiversity refers to the number and variety of these organisms in the biosphere. Due to loss of species at an accelerating rate, there is a challenge in cataloging and understanding the full extent of species diversity. Initiatives to catalog described species with internet aid and organized databases are in place, yet with current rates of species description, it would take centuries to describe all species. This task is made more complicated by ongoing extinction, which is reducing the number of species faster than they can be documented.