ZOO 115 Invertebrate Zoology

Presentation on theme: "ZOO 115 Invertebrate Zoology"— Presentation transcript:

1 ZOO 115 Invertebrate Zoology
Phylum Echiura

2 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

3 Phylum Echiura- external anatomy
Two main body parts Trunk Proboscis (non-retractable) Some have a pair of chaetae similar to Annelids

4 Phylum Echiura- Locomotion
Hydrostatic skeleton (coelom) Peristalsis - Similar to Sipunculids

5 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) Trunk hidden

6 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.

7 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

8 Phylum Echiura- Excretion
Metanephridia one pair two pair in Echiuris hundreds in Ikeda Anal vesicles pick up coelomic waste and transport it to anus

9 Phylum Echiura– Nervous system
Simple – similar to annelids Brain around gut Ventral nerve cord Almost no sensory receptors

10 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

11 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 Male

12 Phylum Echiura – Development
Trochophore larvae Spiral holoblastic cleavage

13 Urechis caupo (Fat Inkeeper)
Commensal species Permanent Pea crab (Scleroplax granulata) Scale worm (Hesperonoe adventor) Clam (Cryptomya sp.) Temporary Goby (Clevelandia ios)