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Numbers of Living Species of Animals in each Phylum
There are over one million species of animals that have been described. Some biologists estimate that up to 50 million more remain to be discovered. Of those that have been described, approximately 86% are insects . About 300,000 species are beetles (order Coleoptera ). The numbers of described species in each phylum of animals (other than the insects ) are shown below. Note that these are only rough estimates . The estimates from other sources may vary considerably.

PHYLUM
Numbers of Living Species of Animals (exclusive of insects)
No. Species
Arthropoda
 
97,000
Mollusca
 
50,000
Vertebrata
 
47,000
Protozoa
 
35,000
Platyhelminthes
 
20,000
Annelida
 
15,000
Nematoda
 
12,000*
Porifera
 
9,000
Cnidaria
 
9,000
Echinodermata
 
7,000
Ectoprocta
 
4,500
Urochordata
 
3,000
Rotifera
 
1,800
Nemertea | 900
Acanthocephala | 700
Gastrotricha | 450
Tardigrada | 400
Sipuncula | 250
Nematamorpha | 230
Kinorhyncha | 150
Entoprocta | 150
Pogonophora | 135
Echiura | 135
Chaetognatha | 100
Ctenophora | 100
Mesozoa | 100
Hemichordata | 85
Onycophora | 80
Gnathostomulida | 80
Cephalochordata | 23
Phoronida | 15
Priapula | 15
Loricifera | 9+
Vestimentifera | 8
Placozoa | 1

* There are probably many more species that are yet undescribed

References:

Barnes, 1980
Brusca, 1990
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