Presentation top top theme: \"Biology thing 37 Mollusks and also Annelids. I. Mollusk & Annelid similarities Both have actually spiral cleavage Both have the formation of mesoderm Both have a.\"— Presentation transcript:

1 Biology thing 37 Mollusks and Annelids

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2 I. Mollusk & Annelid similarities Both have spiral cleavage Both have actually the formation of mesoderm Both have actually a true coelom (eucoelomate) Both have actually trochophore larvae (a trochophore is a larval type that have tufts of cilia in ~ its ends and also a band around the middle) – The trochophore later on becomes a veliger in numerous free-swimming mollusks.

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3 II. Phylum Mollusca “Meaning soft-bodied” Ex.’s clams, snails, oysters, squid, octopi, and chambered nautiluses

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4 Phylum Mollusca Bilateral the opposite Two key body part – head-foot, visceral mass complete body systems current mantle radula

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5 Body setup Have two main body areas (A head-foot and also a visceral mass) A mantle covers and protects the visceral mass. It also secretes a shell. (made of calcium carbonate) The mantle cavity is a room that forms in between the body and the mantle.

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6 Body setup continued… most mollusks space bilaterally symmetrical. Thus they have ganglia. (paired clusters of nerve cells connected by lengthy nerve chords which prolong to the human body muscles and the sense organs) The feeding adaptation the mollusks is a radula. This is a tongue prefer strip covered by difficult abrasive this that allude backwards. (see picture on page 726)

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7 B. Group Gastropoda – stomach-footed, solitary shelled mollusks – Ex.’s = slugs, conches, abalones, and also aquatic and also terrestrial snails. – this organisms experience a process called torsion during development. – have actually an open circulatory system. Your blood dubbed hemolymph walk not stay in vessels. Instead, the is pumped through the dorsal heart and fills a cavity called the hemocoel.

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8 B. Group (continued) Bivalvia - two shelled mollusks. – Clams, oysters, scallops, and also mussels. – referred to as bivalves due to the fact that they have two shells through a hinge connecting them. Hosted together by adductor muscles. – unlike gastropods, bivalves are mostly sessile together they filter feed through the usage of siphons The incurrent siphon draws water end the gills The excurrent siphon sends cleaned water the end of the seashells

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9 Bivalve covering Layers 1. Pearly layer- the smooth, shining layer next to the mantle. - If an grain of sand gets captured in the mantle, the pearly layer builds up approximately the object and forms a pearl. 2. Prismatic layer- middle layer made of calcium lead carbonate 3. Horny Layer- The outermost layer that looks prefer dried varnish.

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12 3. Cephalopoda Head-footed mollusks The foot is usually separated into tentacles well-known for free-living predatory visibility – ex. Squid, octopi, cuttlefish, chambered nautiluses

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13 Cephalopods continued…. Likewise known for a having actually a complex nervous system and also a huge brain. – Can process sensory info. In innovative ways – even can solve straightforward problems and performs complicated tasks together as building their own shelter from ocean debris.

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14 added Characteristics have a closed circulatory system have actually separate sexes save chromatophores, giving them the capacity to suddenly readjust colors

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15 squid 10 tentacles (the 2 longest record the prey while the various other 8 pressure the food into their mouth) The mantle is muscular and also has the ability to pump jet of water with their body enabling them to relocate swiftly many are about 1 ft. In size although the huge squid can reach a length of 60 feet and weigh as lot as 3.5 tons. That is the largest well-known invertebrate.

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16 The Octopus Octopi have actually only 8 tentacles an ext likely to catch prey top top the ocean floor 보다 squid Also around 1 foot in length, although the gigantic Pacific octopus deserve to reach a size of about 8 feet.

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17 III. Phylum Annelida segmented worms, naval worms, leeches

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18 Phylum Annelida cont… Name way little rings and comes indigenous the reality that the human body cavity is split into many sections or segments.

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19 A. General features 2/3 of every annelids space marine, others room freshwater or terrestrial. Body is separated into segments. All major body/organ systems current in annelids. Most have actually bristles or setae and also fleshy protrusions called parapodia.

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20 B. Class 1. Polychaeta (meaning “many bristles” – this organisms are largely marine or discovered in wet sand. – ex. Christmas tree worm, fireworm, and also all maritime worms. Fireworm Christmas tree worm

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21 Polychaetes continued… Unlike other annelids they have antennae and specialized mouthparts castle are additionally the only annelids that have actually the trochophore larvae they live in marine atmospheres and complimentary swim to feeding on small animals 2/3 of all Annelids fit into this course

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22 B. Class (continued) 2. Hirundea – these organisms are external parasites. They have actually an anterior and posterior end and cling to animals with suckers. – ex. Leeches

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23 Hirundea Continued…. The smallest class of annelids (about 30 different species) Live in fresh water Parisitize little animals and also suck your blood Fact- if undisturbed, a leech can ingest 10 time their very own weight in blood

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24 B. Classes (continued) 3. Oligochaeta – this organisms space freshwater or terrestrial and also have few bristles. – ex. Earthworms

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25 IV. Common Earthworm Lumbricus terrestris

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26 A. General features Have about 100 segments. Anterior finish is darker and much more pointed.

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27 A. General features (continued) The mouth is crescent shaped and also underneath the upper lip called the prostomium. The anus is the opened at the posterior end. Both are specialized segments.

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28 A. General attributes (continued) segment 32-37 have actually a distinctive swelling called the clittellum.

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29 A. General attributes (continued) each section other than the an initial and the critical have 4 pair the setae on the bottom and side to assist in locomotion.

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30 B. Digestive system Takes up most of the anterior finish of the body. Has no jaws or teeth, rather uses its’ muscular pharynx to suck in soil.

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31 B. Digestive device (continued) necessary food particles and inorganic floor particles walk through lengthy tube-like esophagus right into a ring organ dubbed the crop. The chop stores the food until it is forced through the gizzard.

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32 B. Digestive mechanism (continued) The gizzard contracts and also expands bring about grains the sand and also food to rub together. Food is finally digested in the intestine. Intestine Food particles

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33 B. Digestive device (continued) digested food is soaked up by the blood circulating through the intestinal wall. Wastes pass the end of the anus.

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34 B. Digestive device (continued) Extra details As worms feed they loosen soil, soil would certainly be very compacted and also hard with out worms. Steps of cradle Mouth – Pharynx - esophagus – crop – Gizzard – Intestine - Anus

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35 C. Circulatory mechanism Blood Flows v a collection of tubes or vessels. ~ digestion, blood dead the commodities of cradle to all body cells.

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36 C. Circulatory system (continued) Earthworm have actually no true heart. Rather the have 5 pairs of pumping vessels referred to as aortic arches.

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37 D. Respiration and also Excretion The skin is protected by a thin cuticle slim skin allows them come absorb oxygen & provide off carbon dioxide. Wastes room passed come the exterior of the body through nephridia. They room a simplistic variation of ours kidneys.

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38 E. Nervous System and also Sense guts Segment number three includes a pair of fused ganglia made up of nerve cells; duty as the brain. Nerves (Ventral Nerve Chord) branch from these ganglia to control the muscles and to get stimuli from every segment.

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39 E. Concerned System and Sense offal (continued) Earthworms have no eyes or ears however are sensitive to light and also vibrations.

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40 F. Muscular System have actually an outer and also inner layer of circular muscle in the human body wall. Likewise have longitudinal muscles. Both of these together, together with setae, are use in locomotion.

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41 G. Reproductive system Are hermaphroditic but do no self-fertilize. Sperm is produce in 2 pair that testes and also stored in sacs dubbed seminal vesicles. A sperm duct tote the sperm to the male genital pore.

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42 G. Reproductive system (continued) eggs are created in the ovaries and mature in the body cavity. Mature egg are lugged by oviducts come the mrs genital pore.

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43 G. Reproductive mechanism (continued) Sperm is passed native one worm to an additional on the spot referred to as the seminal receptacles. The clittellum secretes a slime ring which contains the eggs.


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The eggs space then in turn fertilized by the sperm.

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