The phylogeny of fish

All fish belong to the subphylum Vertebrata which for fish can be separated into the jawless fish (Infraphyla: Agnatha, which includes hagfish and lampreys and jawed fish, belonging to the jawed vertibrates (Infraphyla: Gnathostomata).

The jawless fish can be divided into two classes: cartilaginous fish (Chrondrichthyes), which includes rays and sharks and bony fish (Osteichthyes).

The bony fish contain two classes: ray-finned fish (Actinopterygii) which include the infraclass Teleostei containing almost 96% of all fish species and the lobe-finned fish (Sarcopterygii) that include oa the coelocanths and lungfishes.

More detailed information can be found here.

Compilation by Tonny Mulder Picture credits; CC

Adapted from Sharon Highschool Credits; CC BY-SA 3.0

The anatomy of fish

The anatomy of bony fish is represented here

• Brain [&] spinal cord: Yellow
• Circulatory system: Red
• Reproductive system: Pinkish
• Respiratory system: Grey
• Digestive system: Green
• Swim bladder: Orange

More detailed information can be found here.

The Fish Brain

In general all fish brain can be divided into Six sections from anterior to posterior:

• Olfactory lobe (OB)
• Telencephalon (T)
• Diencephalon (D containing the hypothalamus (Hy) and the pituitary gland (Pi)
• Mesencephalon (M) also know as the optic tectum (OT)
• Rhombencephalon (R)containing the cerebellum (Ce) and the Medula Oblongata (MO)
• Spinal cord
• Also visible: Optic nerve (Opn)

More detailed information on fish can be found here.

The gross anatomy of the largemouth bass (Micropterus salmoides). A: Top, dorsal view, in-situ in the skull. B: Lateral view and C: Bottom, ventral view. Scale bar = 5 mm. From Li et al; 2024 Credits; CC BY-SA 4.0