- labium
- lacinia mobilis
- lacunar
- lamella
- Lanceola
- Lanceolate
- Lappets
- larva
- lateral
- Lateral cirri
- Lateral line
- Lateral lobes
- lateral organ
- Lateral rib
- lateral ridges
- Lateral spine
- Lateral spines
- Lateral tube
- Latticed meshwork
- Le
- Le1
- Le2
- Leaf-cross
- Leaf-star
- Left coiling
- Leg
- Lentelliptical shell
- leptocephalus
- Levogyrous
- Li
- Li1
- Li2
- Li3
- Li4
- Li5
- Li6
- Light organ
- light receptors
- Ligula
- limb
- Lip
- Lip angle
- Lip belly
- Lip flap
- Lip gutter
- Lip rim
- Lip shoulder
- list
- Lobe
- Lock angle
- Lock area
- Lock link
- Lock rib
- Lock system
- Lock tubercles
- longitudinal
- Lorica
- Lower lip
- luciferin
- luciferinase
- Lumbar stricture
- Lunar periodicity
- Lusitanian