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ZOO 115 Invertebrate Zoology. Phylum Echiura. Phylum Echiura (Viper tail)- General Characteristics. “Peanut worms” ~ 250 species Similar to Annelids but NO segmentation All marine benthic Sand, mud, with boring clams Some as deep as 10,000m From 1 cm to 2 m in length.
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ZOO 115 Invertebrate Zoology Phylum Echiura
Phylum Echiura (Viper tail)- General Characteristics • “Peanut worms” • ~ 250 species • Similar to Annelids but NO segmentation • All marine benthic Sand, mud, with boring clams • Some as deep as 10,000m • From 1 cm to 2 m in length
http://www.quadernsdigitals.net/datos_web/proyectos/p_307/bonelia.jpeghttp://www.quadernsdigitals.net/datos_web/proyectos/p_307/bonelia.jpeg http://content.answers.com/main/content/img/McGrawHill/Encyclopedia/images/CE211200FG0010.gif Phylum Echiura- external anatomy • Two main body parts • Trunk • Proboscis (non-retractable) • Some have a pair of chaetae similar to Annelids
Phylum Echiura- Locomotion • Hydrostatic skeleton (coelom) • Peristalsis - Similar to Sipunculids
Trunk hidden http://www.17slon.org/potapljanje/lokacije/hr/istra2/marina016-500.jpg http://www2.ucsc.edu/seymourcenter/images/urechis4.JPG http://content.answers.com/main/content/img/McGrawHill/Encyclopedia/images/CE211200FG0010.gif Phylum Echiura- Feeding and Digestion • Most surface feeders (detritivore) • mucus and cilia on proboscis • gutter for transporting food particles • Suspension feeding • mucus net (Urechis caupo)
http://bio.classes.ucsc.edu/bio136/echiura/echiura.html Phylum Echiura- Feeding and Digestion • Note the relatively straight, but coiled, digestive tract (not U-shaped) • Hindgut gut has a ciliated groove for moving food.
http://bio.classes.ucsc.edu/bio136/echiura/echiura.html Phylum Echiura– Gas Exchange and Circulation • Anal vesicle (sac) used for gas exchange. Body causes water to be pumped in and out of anus. • Closed circulatory system powered by body movements
http://bio.classes.ucsc.edu/bio136/echiura/echiura.html Phylum Echiura- Excretion • Metanephridia • one pair • two pair in Echiuris • hundreds in Ikeda • Anal vesicles • pick up coelomic waste and transport it to anus
http://bio.classes.ucsc.edu/bio136/echiura/echiura.html Phylum Echiura– Nervous system • Simple – similar to annelids • Brain around gut • Ventral nerve cord • Almost no sensory receptors
Phylum Echiura- Reproduction • Urechis caupo has good wound healing but asexual reproduction not known • Sexual Reproduction • Dioecious • Gonad produce gametes • Gametes brought into nephridia and ejected to the outside http://bio.classes.ucsc.edu/bio136/echiura/echiura.html
Male Phylum Echiura – Reproduction • Bonellia sp. • Have parasitic males • Sex determined by proximity of larvae to female proboscis – if close becomes male • Controlled by hormones from proboscis • Males enter female body through nephridia
Phylum Echiura – Development • Trochophore larvae • Spiral holoblastic cleavage
http://academic.evergreen.edu/g/goefre12/symbiosis/commensals.htmhttp://academic.evergreen.edu/g/goefre12/symbiosis/commensals.htm http://en.wikipedia.org/wiki/Image:Pinnotheres_pisum.jpg http://www.amonline.net.au/collections/marineinverts/record.cfm?id=128 http://www.elkhornslough.org/critters/fatworm.htm Urechis caupo (Fat Inkeeper) • Commensal species • Permanent • Pea crab (Scleroplax granulata) • Scale worm (Hesperonoe adventor) • Clam (Cryptomya sp.) • Temporary • Goby (Clevelandia ios)