Trochophore

Trocofora

Larval form of marine invertebrates

A trochophore (also spelled trochophora) is a type of free-swimming planktonic marine larva with several bands of cilia. These larvae are characteristic of marine annelids and most groups of molluscs, as well as other members of the Lophotrochozoa clade, such as nemertea and sipuncula.

Morphology

The trochophore larva is typically spherical or pear-shaped and is girdled by a ring of cilia, known as the prototroch, which is used for swimming and feeding. The mouth is located just posterior to the prototroch, and the anus is located at the opposite end of the body. The apical tuft, a sensory structure, is located at the top of the larva.

Development

Trochophores develop from fertilized eggs and undergo a series of transformations before reaching their adult form. In annelids, the trochophore stage is followed by the development of segments, leading to the adult worm. In molluscs, the trochophore may develop into a veliger larva before metamorphosing into the adult form.

Function

The ciliated bands of the trochophore are essential for locomotion and feeding. The prototroch creates water currents that help in capturing food particles, while the cilia also aid in the larva's movement through the water column. This stage is crucial for dispersal, allowing the species to spread to new habitats.

Evolutionary Significance

The presence of trochophore larvae in diverse groups of Lophotrochozoa suggests a common evolutionary origin. This larval form is considered an important feature in understanding the evolutionary relationships among these groups.

Related Pages

• Annelida
• Mollusca
• Lophotrochozoa
• Larva
• Veliger
• Nemertea
• Sipuncula