Characteristics: In all sea slugs (formerly known as Opisthobranchia) you will find the gills behind the heart. The sea slugs originate from the sea snails which have the gills in front of the heart. The shell is usually internal or completely lost at some point during evolution.The name Heterobranchia means different-gilled snails.he sea slugs originate from the sea snails which have the gills in front of the heart. The shell is usually internal or completely lost at some point during evolution. The name Heterobranchia means different-gilled snails.
The twelve thoracic vertebrae are numbered T1 to T12. The range of motion in the thoracic spine is limited. Lumbar (low back) - the main function of the lumbar spine is to bear the weight of the body. The five lumbar vertebrae are numbered L1 to L5.
The human vertebral column consists of 33 vertebrae. These are divided into different regions, which correspond to the curves of the spinal column. These regions are called the cervical spine, thoracic spine, lumbar spine, sacrum and coccyx. There are a total of 33 vertebrae in the vertebral column.The articulating vertebrae are named according to their region of the spine.There are seven cervical vertebrae, twelve thoracic vertebrae and five lumbar vertebrae.here are a total of 33 vertebrae in the vertebral column. The articulating vertebrae are named according to their region of the spine. There are seven cervical vertebrae, twelve thoracic vertebrae and five lumbar vertebrae.