Dermal papillae (Onychophora)
Feature of velvet worm anatomy
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Dermal papillae are small protrusions on the cuticle of onychophorans, a group of animals commonly known as velvet worms. These structures give the group their common name, as they have a velvet-like feel when touched.[1] Dermal papillae come multiple forms and cover the body of onychophorans in rings known as annulations.[2]
Development
Types
Primary papillae
Talk about structure and make a diagram showing differences between Peripatidae and Peripatopsidae primary papillae[2]
- when found on distal part of foot known as distal papillae
- when found on basal part of foot known as basal papillae
- scale ranks are responsible for velvety feel[1]
Type 1 sensilla
Type 1 sensilla are a specialized variant of primary papilla with a prominent apical piece covered in scales and a sensory bristle with a textured base. These papillae act as mechanoreceptors, giving the animals a sense of touch, and occur in peripatid velvet worms.[2]
Type 2 sensilla
Type 1 sensilla are similar to type 1 sensilla but lack an apical piece and have a far longer bristle.[2]
Spindle-shaped sensilla
Spindle-shaped sensilla are a modified version of Type 1 sensilla that have a large, spindle-shaped apical piece and a short, thorn-like bristle. Like regular type 1 sensilla, these also only occur in peripatid velvet worms. In life, spindle-shaped sensilla make up an array known as the antennal sensory field. This is located on the underside of the antennae on its proximal (closer to the base) portion.[2]
Accessory papillae
Crater shaped papillae
