Platyhelminthes: The Flatworms
Classes
Class Turbellaria: Free Living Worms (these are the ones we will focus on)
Class Trematoda: Flukes
Class Monogenea: Flukes
Class Cestoidea: Tapeworms
Class Turbellaria: Free Living Worms (these are the ones we will focus on)
Class Trematoda: Flukes
Class Monogenea: Flukes
Class Cestoidea: Tapeworms
Anatomy
Platyhelminthes are all triploblastic (meaning they have an ectoderm, mesoderm, and endoderm) and are bilaterally symmetrical. They are acoelomates which means they lack a fluid-filled body cavity. They have a fairly simple body plan.: flattened, soft-bodied, distinct posterior and head area.
Nervous System
Flatworms have rudimentary brain formed by a pair of fused cerebral ganglia. This is attached to nerve cords that run down the body in a ladder-like fashion.
Platyhelminthes are all triploblastic (meaning they have an ectoderm, mesoderm, and endoderm) and are bilaterally symmetrical. They are acoelomates which means they lack a fluid-filled body cavity. They have a fairly simple body plan.: flattened, soft-bodied, distinct posterior and head area.
Nervous System
Flatworms have rudimentary brain formed by a pair of fused cerebral ganglia. This is attached to nerve cords that run down the body in a ladder-like fashion.
Locomotion
Some flatworms have oblique, circular and longitudinal muscles. Some beat their cilia to move.
Circulatory System
Flatworms lack this system.
Respiratory System
These functions are completed by absorption through the skin.
Digestive System
Marine flatworms have a complex, incomplete gut. This means that they have one opening for taking in food and excreting waste. They do have protonephridia that filters waste.
Reproduction
Most are monoecious (hermaphroditic). Many can reproduce sexually or asexually although they have developed ways to avoid self-fertilization.
Some flatworms have oblique, circular and longitudinal muscles. Some beat their cilia to move.
Circulatory System
Flatworms lack this system.
Respiratory System
These functions are completed by absorption through the skin.
Digestive System
Marine flatworms have a complex, incomplete gut. This means that they have one opening for taking in food and excreting waste. They do have protonephridia that filters waste.
Reproduction
Most are monoecious (hermaphroditic). Many can reproduce sexually or asexually although they have developed ways to avoid self-fertilization.