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Metazoa (animals)

Life > Eukaryotes > Opisthokonta

Classification

Porifera (sponges)

 

 

Ctenophora (comb-jellies) 

 

 

Cnidaria (jellyfish, sea anemones, sea fans, soft corals, hard corals)

The unique feature of the Cnidaria is that they have stinging cells, called nematocysts. Each of these cells contains a thread-like sting that is discharged in attack or defense (if you have been stung by a bluebottle while swimming at the beach, you will know all about this). Cnidaria come in two main forms: polyps, that usually stays in one place (e.g. sea anemones), or medusae that have an umbrella shape and float or swim around in the water (e.g. jellyfish). Bluebottles and their relatives (Siphonophora) are unusual in that each of them is basically a colony of floating polyps, one of which is inflated to form the float. So not all polyps are sedentary. Some of the most important members of the Cnidaria are the corals that, in association with symbiotic algae, are able to lay down calcium carbonate and in this way build whole islands that people now live on.

 

Placozoa

Trichoplax adhaerens, an amoeba-like marine animal about half a centimeter long, is the sole species known from this phylum.

 

Bilateria

 

 
 

Deuterostomia

 

 
   

Chordata (vertebrates and relatives, including fish, mammals, birds, reptiles and amphibians).

Have a dorsal nerve cord and a notocord (that becomes the vertebral column in vertebrates).

   

Ambulacraria

 

 
     

Hemichordata

Marine organisms such as acorn worms.

 
     

Echinodermata (starfish, sea urchins, sea cucumbers, etc.) 

 

 
 

Ecdysozoa

 

 
   

Gastrotricha

About 430 species known, all microscopic.

 
   

Introverta

 
     

Nematoida

 

 
       

Nematomorpha (horsehair worms)

About 320 species known.

 
       

Nematoda (nematodes or roundworms)

About 12000 species known, but an estimated 200000+ species extant, mostly microscopic. Considered the second most diverse animal phylum after the arthropods.

 
     

Cephalorhyncha (= Scalidophora)

 
       

Priapula (priapulid worms)

Sixteen species known, about half microscopic.

 
       

Scalidorhyncha

 
       

 

Kinorhyncha (mud dragons)

About 150 species known, all microscopic.

 
         

Loricifera (loriciferans)

 
   

Panarthropoda

 
      Onychophora (peripatus)

 

     

Tritocerebra

 
       

 

Tardigrada (water bears)
     

 

 

Arthropoda (insects, spiders, scorpions, crustaceans, centipedes, millipedes)  
 

Lophotrochozoa

 

 
    Platyhelminthes (flatworms, tapeworms)  
   

Rotifera (rotifers or "wheel animalcules")

 About 1500 species known, all microscopic.

 
   

Cycliophora

 

 
   

Entoprocta

 

 
   

Bryozoa

[= Ectoprocta]

 

   

Annelida (segmented worms, including earthworms and leaches) 

 

 
   

Nemertea (ribbon worms)

Marine worms that in some species can reach 30 m in length! Synonyms: Nemertini or Nemertina.

 
   

Sipunculida (peanut worms)

[= Sipuncula]

Marine.

 
    Mollusca (snails, mussels, squid, etc.)  
   

Echiura (spoon worms and innkeepers)

Marine. Once placed with the phylum Annelida.

 
   

Siboglinidae (beard worms)

[= Pogonophora, Vestimentifera]]

Marine worms living in tubes. Some giant species, 1.5 m long have been found around warm water vents in the Pacific Ocean. Siboglinidae has been placed previously under the Annelida.

 
   

Phoronida

 

 
   

Brachiopoda (lamp shells)

Look superficially like clams in that they have a similar shaped shell but they are not molluscs. 

 

Unplaced

Chaetognatha (arrowworms). About 70 species known.  
Acanthocephala. Spiny-headed parasitic worms; about 1150 species known.  
Gnathostomulida   
Monoblastozoa   
Rhomobozoa  
Orthonectida  

How animals are given scientific names - a brief introduction

Text by Hamish Robertson 


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