Marine annelid diversity Specialized Taxa Class Polychaete family Siboglinidae Pogonophora and Vestimetifera Class Sipuncula Class Echiura Class Clitellata Oligochetes and Leeches

Annelid Diversity: “ Family Siboglinidae Polychaeta SubFamily Vestimentifera vent worms and seep worms SubFamily Frenulata Genus Osedax (whale carcass worms) “

Annelid Family Siboglinidae “... small but very intriguing group…” Includes Frenulate “spaghetti worms” that feed by absorbing nutrients Whale carcass worms: root system absorbs bacterial nourishment from bone marrow; & symbiotic bacteria Vestimentiferan giant cold seep and hot vent worms Live deep in the ocean No digestive system Thrive in areas of high methane or sulfur

Sub Family Frenulata < 1mm diameter 10 - 74 cm long (spaghetti-like worms) opisthosoma 6-25 segments containing coelomic compartments that are isolated from each other by muscular septa; each segment bears chitinous setae Fig 13.12-13.14

Sub Family Vestimentifera Large thick bodies, up to 2 m long vestimentum

Whale fall time series Hagfish Sleeper sharks Polychaete worms (free living, bacterial grazers) Vigtorniella (Polychete) Whale carcass worms Osedax not considered Vestimentiferans

A watercolor painting shows females and males from the new marine worm species. The female worms are illustrated both in their tubes and with a whalebone “cutaway,” to reveal their large ovisacs and extensive roots that invade the bone. The small males live in the tubes of the females and are shown as “blowups” with their relative positions in the tubes indicated by the dark lines. Top left: male Osedax rubiplumus. Top right: female Osedax rubiplumus. Bottom left: male Osedax frankpressi. Bottom right: female Osedax frankpressi.

Whale Falls A sunken carcass provides a massive food fall for the normally organic-poor deep-sea floor. (i.e. 40 ton whale (2 million g C) Provides an amount of carbon to one hectare that is equivalent to 100-200 yr fallout from the epipelagic zone

F. Siboglinidae Vestimentiferans vent worm Riftia plume heart tube V blood vessel trophosome tube Fig 13.15-16

Read Research Focus 13.1 on Chemosynthesis Microbiologically analogous to Archean vent systems and may serve as models for the origin and evolution of life in Archean vents. Baross ad Hoffman (1985) in Origins of Life and Evolution of Biospheres …deep-sea hydrothermal vents may help advance the understanding of how early microbial life forms gained a foothold in hydrothermal systems on early Earth and potentially on other planetary bodies. (McCliment et al., 2005, Environmental Microbiology 8: 114-125) An alternative proposal to the “pre-biotic soup” theory…chemical conversions that involve “transition metal sulphide catalysts” create favorable environments for abiogenic acetate production that release energy… acetyl-coA is the most central carbon backbone in microbial metabolism Martin et al., 2008, Nature Reviews 6: 804-14

Newest Siboglinidae Osedax Rouse, GW. et al. 2004 (not a vestimentiferan) Scleolinum is a deep water warm described only along the coast of norway. It has only two tentacles, an opisthosoma of 11 segments. Osedax Rouse, GW. et al. 2004

Newest Annelids Class Sipuncula (peanut worms) Class Echiura (inn keeper worms)

Some Annelid (Echiura) vs Sipuncula Characteristics Annelid-like Characteristic Echiura Sipuncula Musculature outer circular and inner longitudinal Setae Present Absent Metamerism early juvenile Absent Coelom form. All have schizocoelous formation Cleavage All with spiral determinate cleavage Larval form The trochophore is the first larva

Phylogeny of Annelida In Flux Among the Eumetazoa, within the lineage of Lophotrochozoa that includes molluscs Annelida monophyly is somewhat accepted with unique characters of segmentation and setae Phylogeny within the Annelida in turmoil over last 15 yr

Whither Polychaeta? Evolution of Clitellata? Nuclear genes and 2007 Family Capitellidae Nuclear genes and rDNA sequence analyses Family Terebellidae Whither Polychaeta? Evolution of Clitellata? Family Nerididae Taxonomic Families traditionally considered to be polychaetes

Annelid Taxonomic Classes: Clitellata Oligochetes (Covered as contrast to polycheate adaptations) Hirudineans

leech “Clitellata” Leeches are highly specialized annelids that have fundamental features in common with oligochetes Clitellum Coccoon No parapodia No head appendages leech “Clitellata”

Phylogeny of the Annelid Classes Arctic salmon worms Crayfish worms ? Parapodia Complex head Body sucker Clitellum, hermaphroditism Annelid head, setae bundles

In comparison to polychetes, the head is reduced, parapodia Fig 15.20-21 In comparison to polychetes, the head is reduced, parapodia are lacking, circulatory system is more elaborate. Locomotion...

anchoring system that prevents Locomotion in Oligochetes ...Relies on the hydrostatic Skeleton for movement and for circular and longitudinal muscle extension. The setae act as an anchoring system that prevents backward slippage

Complex Reproductive System Viewed as Adaptive to Terrestrial habitat

A sperm receptacle sperm sack A Fig 15.19 The mating process is no simple shedding of gametes Pair appose ventral surfaces, with anterior pointing in opposite directions. Each worm then surrounds itself in a mucus cocoon and sperm is exchanged

Embryos are in a protective cocoon

Sub-Class Hirudinea Live primarily in fresh water 3/4 of all spp are sanguivores Similar to earthworms in reproductive behavior and repro. morphology: “Clitellata”

General Body Form

General Body Form Most lack setae Body not separated by septa crop Nephridial vessel cecum mesenchyme testis Most lack setae Body not separated by septa Continuous coelomic space filled by mesenchyme Channels and sinuses serve a blood transport function

leeches are also graceful Locomotion in Leeches With no hydrostatic skeleton or parapodia, leeches use their suckers to loop over a substrate. Aquatic leeches are also graceful swimmers.

--Bladelike jaws --Muscular pumping pharynx --Pharynx also releases an anesthetic, a vasodilator, and Hirudin, an anticoagulant. --They drink 5-10 times their body weight. Bleeding can continue for hrs after bite. --Symbiotic bacteria slowly break down the blood. Digestion of a meal may last for weeks. --Hirudin keeps blood from clotting in the gut

Medical Applications Key event in final stages of clotting Leeches applied in cases where scars, grafts or other tissues suffer from lack of circulation Hirudin is a thrombin-specific inhibitor. Hirudin or laboratory analogs used to reduce threat of clots. Key event in final stages of clotting fibrinogen -------------------> fibrin (serine protease) Thrombin enzyme insoluble protein soluble protein Ca++ Hirudin is a direct thrombin inhibitors (natural antithrombin III) bind directly to thrombin and are active against free circulating thrombin as well as (‘clot-bound thrombin’). Prothrombin --Thrombin enzyme Draculin in vampire bats: prevents final step in prothrombin synthesis, thereby inhibiting production of clotting factor thrombin