ZOO 115 Invertebrate Zoology Phylum Onychophora Onychophora Talon

ZOO 115 Invertebrate Zoology Phylum Onychophora

Onychophora (Talon bearer)General Characteristics n n n Common name: Velvet worms Intermediate between annelids and arthropods ~110 species Fossil records from Early Cambrian period (~530 MYA) Terrestrial n Dark humid tropical regions http: //www. mnhn. fr/assoc/myriapoda/IMAGES/OOPERIHI. JPG

Onychophora - General Characteristics n n n Soft-bodied Wormlike 5 mm-15 cm in length Segmented with serial repetition of organs http: //www. cals. ncsu. edu/course/zo 150/mozley/fall/Onychophora. jpg

Onychophora – Support n Body is covered by thin chitinous cuticle n n n Similar to arthropods Highly permeable Flexible n Accordion-like Circular/Diagonal muscle Longitudinal, circular, diagonal and surface oblique muscles Body wall, other than cuticle, similar to Annelids Hemocoel Slime glan Oblique muscle Attached to surface

Onychophora - Locomotion n Trunk bears 13 -43 pairs of appendages n n n with claws Like parapodia of polychaetes Operated as part of the hemocoel http: //www. jcu. edu. au/school/tbiol/zoology/pictures/peripat 5. jpg http: //www. jcu. edu. au/school/tbiol/zoology/pictures/peripat 2. jpg

Onychophora - Nutrition n Carnivores - eat small arthropods n n Secrete jets of slime up to 30 cm to entangle prey Lacerate prey with mandibles (jaws) Secrete saliva with hydrolytic enzymes Pharynx pumps liquid food into stomach http: //www. cals. ncsu. edu/course/zo 150/mozley/fall/Onych ophanat. jpg

Onychophora - Digestion n n Chitin-lined foregut (pharynx and esophagus midgut (intestine – digestion and absorption Slime gland http: //www. cals. ncsu. edu/course/zo 150/mozley/fall/Onychophanat. jpg

Onychophora - Excretion n n Anus for solid waste Nephridia - like arthropods http: //www. cals. ncsu. edu/course/zo 150/mozley/fall/Onychophanat. jpg

Onychophora – Circulation n Open system similar to arthropods n n n Heart tubular heart with pericardial sinus large hemocoel Hemocoel Gas exchange n n small openings in each segment– Spiracles lead to tracheal tubes From Brusca and Brusca (2003) Nephridia

Onychophora - Nervous system n Ladderlike nervous system - like both annelids and arthropods n Paired ventral nerve cord n Sensory n n n Antennae Eyes at base of antennae Sensilla on sensory papillae http: //www. cals. ncsu. edu/course/zo 150/mozley/fall/Onychophanat. jpg

Onychophora - Reproduction n n Separate sexes Sexually dimorphic n n Sperm transferred by spermatophore n n Males smaller In Peripatopsis, spermataphores placed anywhere on female, her cuticle temporarily dissolves and takes up the sperm. Most bear live young