Anatomy & Physiology

Leptothecata have developed specialised morphological and physiological adaptations 

Statocysts
The statocysts found along the outer ring of the Leptothecata medusa are small organs used to determine their orientation and help with balance. 

Radial canal
Leptothecata have four distinct radial canals which connect the stomach to the circular canal on the outer ring of the medusa. Gonad sacks are connected to each one

Mesoglea
A jelly layer found on the medusae. While scyphozoans contain amoeboid cells in the mesoglea, Hydrozoans lack the presence of any cells here. 


 

 
Close up of the centre of the medusa

Polyp stage of Hydrozoa
 
Hydrozoan polyp adapted from Ruppert, Fox & Barnes 2004.