Vermes (Worms) with various sense organs to inspect and evaluate the environment Linnaeus – 1st to propose a formal classification of all life on earth the elongated shape also allows the animal to fit into cracks and crevices and to easily burrow through à most invertebrates were lumped together the sediment as “vermes” = worms in most worms the mouth is also at the front end of here we will use the term to refer to an assortment of the animal animals (Many different Phyla) that share a similar wormlike body plan worms are poorly known in the fossil record but “trace fossil” such as burrows & trails have been found 1. elongate cylindrical body from 565MY ago
2. all are invertebrate animals à probably were the first kind of animals that moved (ie. were not sessile) (doesn’t include snakes, eels, etc) à may be first animal to have a head & tail 3. here we are only including those in which the adults are free –living today worms occur in almost every kind of habitat from arctic to tropics: ànot worms that are parasites ocean, hot springs, lakes, ponds, soil, ice, etc the worm-shaped body is one of the most common, versatile and adaptable forms in the animal live in crevasses, old shells, burrows or self kingdom constructed tubes
it allows for a distinct “front end” or head most worms live in or on the bottom sediment in marine and freshwater habitats, or in soil on land since the head is the part of the body that meets the environment first it is usually equipped most worms are microscopic to several inches
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but the longest animal in existence is a ribbon Acorn Worms (Hemichordata) worm
= ~180’ (60 M) long Movement
as a group worms are probably the most abundant most worms have a muscular body wall with 2 animals on earth layers of muscles:
eg. est 6 M individuals in 1 ft3 of soil circular and longitudinal muscles eg. upper 1” of rich soil may contain >1 Bill/acre allows worm to both constrict and elongate the à virtually every soil sample will yield new body by contracting against a fluid filled body species cavity
in the ocean worms are also probably the most abundant animal in and on the sediment =hydrostatic skeleton many worms are brightly colored some have pairs of stubby legs or flaps that help them
some white, red, yellow, green, purple to move, swim, crawl, and dig today many different unrelated animal groups have Feeding & Digestion these wormlike characteristics in common: most worms have a complete digestive tract Ribbon Worms (Nemertea) Gastrotrichs (Gastrotricha) Thread Worms (Nematoda) with both a mouth and an anus Horsehair Worms (Nematomorpha) Sand Worms (Polychaetes) à one way path from mouth to anus Earth Worms (Oligochaetes)
Velvet Worms (Onycophora) much more efficient than the digestive sac of corals Peanut Worms (Sipuncula) jellyfish & planarians Spoon Worms (Echiura)
Beard Worms (Pogonophora) Priapulids (Priapulida) worms feed in a variety of ways: Horseshoe Worms (Phoronida) Arrow Worms (Chaetognatha) a. carnivores Animals - Vermes; Ziser Lecture Notes, 2017.5 3 Animals - Vermes; Ziser Lecture Notes, 2017.5 4 b. scavengers & deposit feeders c. filter feeders usually have two nerve cords extending from the ______simple brain down the length of the body from the mouth, food moves into the digestive tract often with ladder-like interconnections the complete digestive tract is typically modified into a head usually contains several sense organs: variety of specialized structures: simple eyes (=ocelli) pharynx – surrounded by muscles to pumps food in most can’t form images, only detect light crop: food storage area a few polychaete eyes have cornea, lens, retina gizzard: thick and muscular; helps physically break up food à can form images
intestine: the first part of intestine is used for chemical chemical receptors digestion; secretes digestive enzymes
eg. planarians have auricles for touch and chemical senses the remainder is used for absorption on the sides of their head
Circulatory System balance organs (=statocysts)
most worms have a true closed circulatory system tentacles & palps à touch with a pumping heart and blood to carry oxygen
and protect from pathogens
Nervous System worms were probably the first creatures to have some semblance of a “brain”
very simple brain-like ganglia in head
mostly reflex responses, no higher processing
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use eversible proboscis (=pharynx) to capture eg. Ribbon Worms prey slender, very fragile ribbonlike worms often at front of proboscis is sharp pointed spear- like stylet that impales prey most <20 cm(~8”) often tipped with poison some of the longest known animals, up to 180’ eat earthworms, sea worms, small mollusks and regardless of length most are <1” (23mm) wide any small soft bodied animal almost all are marine “Nemertea” translates as “unerring one” they build slime houses: curl up into balls and secrete à refers to animals ability to very accurately shoot its long proboscis to capture prey a covering of mucus around themselves sometimes impales with such force that it breaks fairly common on beaches; often inside dead off shells writhes for hours; animal can grow a new one
à resemble tangled mass of slimy string like snakes they can devour animals larger than themselves arctic ribbon worms commonly wash ashore by the billions have complete digestive tract with anus often very brightly colored without food some can live up to 1 yr by self digesting like planarians some white, red, yellow, green, purple most can shrink at will to < 1/3 their ordinary length a few are found in moist soil or freshwaters
ribbon worms reproduce both asexually and sexually ribbon worms are carnivores
Animals - Vermes; Ziser Lecture Notes, 2017.5 7 Animals - Vermes; Ziser Lecture Notes, 2017.5 8 some reproduce asexually by fragmentation eg. Horsehair Worms
can break into 100’s of fragments also called “gordion worms” or “hairworms”
each fragment can grow into a complete worm adults are free living and abundant in aquatic and moist environments have a circulatory system and simple excretory system àworldwide distribution have a nervous system with brain and nerve cord often found in puddles after rain usually contorted into knots sexually, most are dioecious in old days were common in horse troughs some fragment in warm weather and reproduce sexually in colder weather once thought they were literally produced from horses hairs
in days past: Human Impacts of Ribbon Worms every summer kids would pull hairs out of horses tail and place them in a jar of water put on window ledge in the sun one species found near San Francisco is blamed for watched and waited to see the “transformation” the collapse of the dungeness crab fishery long thin dark reddish-brown
it eats about half of the egg production of the crab really do resemble the hair of a horses tail population
other coastal nemerteans have devastated clam beds have digestive and nervous systems and a few sense organs In South America a couple of species are sold as fish bait (locals call them “tapeworms”)
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Threadworms (Round Worms) à anywhere there is organic matter
= eel worms; round worms have been found in deep ocean trenches and in hot springs & ice long, threadlike cylindrical shape, tapered at both ends, with few distinctive features visible the deepest living animal known is a nematode that lives in fractured rock 0.8 miles deep difficult at first glance even to distinguish front from back à almost 3 times deeper than any other animal most are very small 100th of an inch to 1/5th inch (its DNA was found >2 miles below ground) most are colorless or transparent threadworms are especially common in soil very common and diverse group but poorly known as numerous in soil as arthropods nematodes may actually be second only to arthropods eg. est 6 M individuals in 1 ft3 of soil in number of species eg. upper 1” of soil may contain <1 Bill/acre over two hundred species have been found in a spoonful of beach mud eg. 3.5M/m2 in tundra soils to 9M/m2 in grassland soils in terms of sheer numbers, nematodes are probably à virtually every soil sample will yield new the most abundant animal on earth species
à 4 of every 5 animals on planet are nematodes
à 90,000 nematodes were found in a single rotting apple occur in virtually all habitats from arctic to tropics; marine, freshwaters, and especially in soil
there is virtually no part of the biosphere that doesn’t harbor nematodes Animals - Vermes; Ziser Lecture Notes, 2017.5 11 Animals - Vermes; Ziser Lecture Notes, 2017.5 12
à some can survive mercuric chloride solutions that would “If all the matter in the universe except the kill most other animals nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied à only living organisms to survive a space shuttle explosion spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and eg. 6 canisters of C. elegans survived the Columbia oceans represented by a thin film of nematodes. disaster The location of towns would be decipherable, since for every massing of human beings there would be allows them to survive in many unusual habitats a corresponding massing of certain nematodes.
Trees would still stand in ghostly rows eg. hot springs representing our streets and highways. The location of the various plants and animals would eg. water in pitcher plants still be dieipherable, and, had we sufficient knowledge, in many cases even their species could eg. acidic habitats; rotting fruits, vinegar, stale beer be determined by an examination of their erstwhile nematode parasites.” -N. A. Cobb, 1914, Yearbook of eg. vinegar eels the US Dept of Agriculture, p. 472 a very common soil animal
feeds on rotting fruit fixed number of cells in adult of each species (eutely) before vinegar was pasteurized it was usually found in outside of body is covered with flexible cuticle commercial vinegars (cider vinegar from fermented apples)
à protects worms from abrasion in soil and a related species is found in pitcher plants sediment another species has only been found in the felt coasters under beer mugs in German pubs à protects parasites from digestive enzymes a single layer of muscles in body wall produces a cuticle is sometimes molted as animal grows distinctive side to side thrashing movement
their cuticle is highly resistant to fairly extreme all threadworms eat living cells; plant, animal, environments and conditions bacteria, etc.
à some can survive pH’s from 1.5-11.5 Animals - Vermes; Ziser Lecture Notes, 2017.5 13 Animals - Vermes; Ziser Lecture Notes, 2017.5 14
a muscular throat (=pharynx) allows them to suck they are fundamental in recycling nutrients in all in cells and fluids ecosystems
some have syringe like tube to penetrate prey eg. they play an important role in the nitrogen cycle by helping to mineralize nitrogen complete digestive tract they also help to decompose toxins and wastes well developed nervous system and excretory system soil nematodes help to aerate the soil some can enter a state of arrested activity nematodes help regulate soil bacterial populations (= cryptobiosis) and overall community composition
à makes them successful in seemingly eg. one nematode can eat up to 5000 bacteria /minuite unfavorable environments Human Impacts eg. some have been dried for several years then rehydrated c. Caenorhabditis elegans important biological eg. some have been placed in liquid air (-194ºC “model” in research (one of a handful; eg. lab rat, (= -317ºF)) and revived afterwards fruit fly, E. coli, etc
used to study: genetics, nervous physiology, cell Ecology of Threadworms physiology, aging, etc. while rarely studied and relatively unknown, we know: nematodes occur in large numbers in virtually every habitat its complete wiring diagram of nervous system
origin and embryological lineage of all 959 cells making up threadworms are of enormous ecological importance: its body
they feed on a variety of organisms and are an entire genome of 19,820 genes has been mapped important part of all food webs especiall in soil Animals - Vermes; Ziser Lecture Notes, 2017.5 15 Animals - Vermes; Ziser Lecture Notes, 2017.5 16 Sand Worms à swimming (Bristle Worms) à as gills for respiration sand worms, bristle worms (=polychaete), fan worms, clam worms, etc à used as anchors while burrowing or to prevent capture
à to create feeding currents inside tubes all are aquatic; mostly marine; worldwide distribution à converted into feathery appendages to filter water
most 2-4” long (5-10 cm) ; some up to 10’ (3 M) à as protection or camoflage
often brightly colored well developed organ systems
deposit feeders, filter feeders, predators, scavengers, many are predators, some filter feeders, and
scavengers live in crevasses, old shells, burrows or construct
tubes
some have elaborate filtering structures
eg feather duster worms most are dioecious most have a distinct head and long segmented body some polychaetes live most of the year as sexually immature individuals head with pharynx and chitinous jaws
tentacles palps and sensory structures eg. palolo worm
have a pair of flaplike parapodia, each with many after living 1 or 2 years as benthic organisms they become sexually mature and swollen with bristles (=setae) on each segment gametes (egg or sperm)
these parapodia have a variety of functions and create head shrinks, body enlarges, gonads develop and produce egg or sperm many bizzare shapes:
à crawling or digging in the sediment
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sometimes only part of the body makes the transformation, breaks off and the rest of the Economic Impacts of Sand Worms worm lives to repeat next season
eg. human food (samoa) males and females gather by the millions in one spot
at night determined by phases of the moon eg. insecticides female releases pheromone eg. Padan – a powerful insecticide produced from a polychaete pheromone excites male to circle about female worm
epitokes break off the worm and rise to the surface eg. anticancer drugs
anterior portion of worm returns to burrows eg. dolastatins from sea hare (Dolabella auricularia) has potential anticancer properties swarms of epitokes appear at start of moon’s last quarter in October or November
à sea is literally thick with epitokes
just before sun rises, epitokes burst to release gametes
=synchronous mating
àensure most eggs are fertilized
àpredator saturation
predators have a field day; but too many prey so some are always left to reproduce
a Samoan holiday to feast on epitokes
Ecological Role
very important in food webs of marine ecosystems
Animals - Vermes; Ziser Lecture Notes, 2017.5 19 Animals - Vermes; Ziser Lecture Notes, 2017.5 20 Earthworms eg. Earthworms
burrow within the upper 30 cm of moist soil rich in organic relatives of sand worms but no distinct head, no matter parapodia and few setae eat as they burrow then let digestive system extract nutrients mostly terrestrial; often present in high numbers on warm damp nights, forage for leaves and organic (roundworms are much more abundant but microscopic) debris
rich soil contains 1 ton of earthworms/acre up to 54,000 earthworms /acre
very small mudworms up to 40,000/M2 in rich muds à turn over 18 tons of soil per year
prefer moist soil but if too much water they will move to some tropical earthworms get up to 9’ (3 M) long surface most are scavengers on decaying organic matter à sometimes in great numbers
à used to think they “rained” down from the sky mainly burrowers have circulatory system with 5 pairs of hearts eat as they burrow then let digestive system extract nutrients and hemoglobin in blood to carry oxygen
Reproduction well developed digestive tract:
mouthà pharynxàesophagusàgizzardàintestineà anus earthworms are hermaphrodites
pharynx - pumps food in copulation involves a double exchange of sperm cells crop - temporarily stores food gizzard - muscular, lined with cuticle, grinds food intestine - most chemical digestion and absorption mucous secreted from clitellum holds pair together with genital pores aligned allows them to eat soil and then the intestine sorts out the nutrients for absorption can last 2-3 hours
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sperm is deposited in the others seminal receptacle (with very few exceptions) has been in an earthworm’s stomach before it was part of you.” after copulation worms return to burrows important in keeping soil fertile since they are fertilization and egg laying occur a few days later constantly turning over earth and mixing
each worm secretes a sheath of mucous around organic matter into it clitellum if all material ever moved through earthworm gut was piled clitellum then secretes nourishment for egg on surface of earth it would rise 30 miles above sea level (5x’s height of Mt Everest) then envelopes mucous and food in tough chitin-like cocoon 2. Food for birds and other animals
the worm then backs out of the cocoon Human & Economic Impacts of Earthworms as cocoon slips over the genital openings it receives an egg, then sperm 1. Food for Humans
fertilization occurs in the cocoon in some parts of Asia, Africa and Latin America people regularly eat worms cocoon is deposited in soil usually because there is not much other food available in 2-3 weeks a new worm emerges a few restaurants in the US offer them as novel food fare Ecological Effects of Earthworms 2. earthworms improve the productivity of farm soil earthworms are extremely important in the texture and fertility of the soil sometimes doubling or tripling crop yields
Aristotle referred to them as “the intestines of the earth” 3. Fishing bait
Darwin wondered whether there was any other animal that worms are commonly used for freshwater fishing has played so important part in the history of the
world as earthworms nightcrawlers, redworms
“Earthworms are miniature topsoil factories, they make soil. over 400 Million worms are sold in US and canada as a $50 ALL other (terrestrial) living things eventually pass Million industry through an earthworm on the way to becoming soil.
And it is likely that nearly every atom in your body Animals - Vermes; Ziser Lecture Notes, 2017.5 23 Animals - Vermes; Ziser Lecture Notes, 2017.5 24 Velvet Worms 4. Vermicomposting (Phylum Onycophora)
using worms to recycle compost an ancient phylum originally marine but today all worm castings are sold as a type of enhanced planting soil species are found in tropical forests
5. Bioinvasives live in crevaces and under logs
while many worms are thought of as beneficial northern states (eg Minnesota) are being invaded by the common European body is covered by colorful scales giving them a nightcrawler is destroying the forest floor and wiping out velvety appearance native wildflowers
this part of the country has no native earthworms front end with pair of antennae
they have up to 23 prs of stubby legs, each with claws
àlooks like slugs with legs
thought to be a mollusc when first discovered in 1826
mostly nocturnal
àtend to avoid light
most species are nocturnal predators
mouth with a pair of long claw-like mandibles
àfeed on snails insects and worms
capture their prey or defend themselves by shooting sticky slime up to 30”
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once captured they secrete enzymes (salivary secretions) into prey to partially digest it Beardworms before eating Beardworms are at the base of an entire ecosystem that doesn’t use photosynthesis
discovered in 1900; today 150 known species
most live in deep ocean
àcommon in hydrothermal vent communities
no digestive tract
they get most of their nutrients from symbiotic bacteria living in an organ (=trophosome) within the trunk of the worm
bacteria harvest energy from H2S and convert it into sugars for the worm
CO2 + H2S + O2 + H2O à H2SO4 + sugars
have well developed circulatory system containing hemoglobin
use hemoglobin to carry oxygen to body cells
and to carry oxygen and hydrogen sulfide to bacteria
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In 2001 found red fuzz on whale carcasses in deep ocean
1000’s of worms with red plumes up to 6 cm long seem to be unique to “whale fall” bone worms have no functional mouth or gut have symbiotic bacteria that digested oil in bones the bacteria live in rootlike structures of worm that extend in and throughout the bone worm provides oxygen via blood vessels extending into the roots
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