Higher Invertebrates
phylum mollusca
Characteristics
- coelomic (true coelom) means muscle around gut for coordinated digestion
- protostomes (blastopore develops into mouth)
- ventral muscular foot
- visceral mass dorsal to foot
- mantle (tissue layer that covers visceral mass)
- sexual reproduction (separate sexes)
- some organisms in this phylum (polyplacophores) display primitive segmentation
- share the same type of larvae with annelids (trochopore larvae)
- Considered a living fossil
- primitive
- Looks like a limpet but are found deep in the ocean
- exclusively marine
- eight dorsal plates
- primitive
- have very basic segmentation
- have radula scrapers to feed on algae
- ex. chiton
- lack of shell; these organisms secrete calcium-based spicules and appear shiny because of this
- worm-like animals found deep in the ocean
- ex. chaetoderma elegans
- largest class
- may or may not have a shell
- live in freshwater, saltwater, and on land
- single spiral shell (if they have a shell)
- well developed senses
- can do torsion (rotate their digestive system so that their anus is over their head)
- ex. snails, slugs, nudibranchs (sea slugs)
- live burrowed in marine mud, head down
- tusk shaped shell
- shell open at both ends (unique to scaphopods)
- ex. tusk shelled organisms
- most highly advanced mollusks
- have vertebrate eyes (eyes that are only found in vertebrates)
- capable of learning
- very motile predators
- largest invertebrates
- shell greatly reduced
- ex. octopus, squid, cuttlefish, nautilus
- have two hinged shells (valves)
- filter feeders
- sessile
- use gills for respiration and feeding
- ex. clams, oysters, scallops, mussels
phylum mollusca lab
Analysis Questions
1. The arms are short and have suckers all along the inside of them. The tentacles are longer and have suckers only at the end. There are more arms than tentacles. Both are found on the ventral region.
1. The arms are short and have suckers all along the inside of them. The tentacles are longer and have suckers only at the end. There are more arms than tentacles. Both are found on the ventral region.
2. Cephalopods
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Bivalves
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3. The squid we dissected was male. The reproductive organs were a milky colour. A female’s reproductive organs would have been yellowish and translucent.
4. The food enters through the mouth, then passes through the digestive gland, then passes through the stomach, then the crop. The nutrients are absorbed and wastes are excreted through the anus.
5. The brachial hearts are close to the gills so that oxygen has to travel a shorter distance to the circulatory system. The close proximity of the organs allows for quicker gas exchange.
4. The food enters through the mouth, then passes through the digestive gland, then passes through the stomach, then the crop. The nutrients are absorbed and wastes are excreted through the anus.
5. The brachial hearts are close to the gills so that oxygen has to travel a shorter distance to the circulatory system. The close proximity of the organs allows for quicker gas exchange.
phylum annelida
Characteristics
- coelomic (true coelom) means muscle around gut for coordinated digestion
- protostomes (blastopore develops into mouth)
- specialized digestive organs (prostomium, mouth, pharynx, esophagus, crop, gizzard, intestine, anus)
- nervous system made of ventral nerve cord with an anterior brain
- land forms respire through skin and rely on diffusion (aquatic forms have gills)
- sexual reproduction with very limited regeneration (hermaphroditic)
- simple segments separated by internal septa
- specialized excretory system (nephridia)
- triploblastic
- bilateral symmetry
- closed circulatory system
- simple segmentation
- live on land
- must stay moist (respire through skin)
- move using setae (little grippers on the side of the skin)
- head and sensory organs reduced
- when the reproduce sexually, the clittelum makes a lot of mucous and two earthworms rub against each other and swap sperm
- ex. earthworms
- live in water
- parapodia (used as paddles) instead of setae
- gills
- ex. sandworms
- ectoparasites
- feed on the blood of vertebrates
- most common in fish
- secrete an anticoagulant (prevents blood clots) and an anesthetic (numbs the area) into the host
phylum annelida lab
Analysis Questions
1. An earthworm has five hearts (also called aortic arches) that pump blood through their circulatory system.
2. The prostomium shovels dirt into the earthworm’s mouth. The food passes through the pharynx, the esophagus, the crop, the gizzard, and the intestine. It is excreted through the anus.
3. The ganglion in the anterior region. It is connected to the ventral nerve cord which runs the length of the worm.
4. The nephridia.
5. By cutting open any part of its digestive system (the intestine is probably the best) and examining the contents.
6. Since earthworms live on land, they need something to help them move along the earth. The setae are a useful adaptation because allow the earthworm to move easily by gripping the soil and allowing the worm to propel itself forwards.
7. The digestive system has specialized organs within it that allow the worm to absorb the small amount of food found in the dirt it ingests. The intestine is also large and has a lot of surface area to maximize the amount of nutrients that can be absorbed.
8. If we had have gone past segment 32, we would have seen identical segments. Within those segments would have been nephridia and the intestine.
9. The ectoderm develops into the skin and the nervous system, the endoderm develops into the digestive system (the intestine, the crop, and the gizzard), and the mesoderm develops into muscle and the remaining organ levels (the circulatory and reproductive systems). The muscle is attached to the skin and the digestive system with a cavity in between called the coelom.
10. The function of the nephridium is to filter the coelomic fluid. Coelomic fluid from the previous segment enters into the nephridium through the nephrostome. The nephridium filters out the good things in the coelomic fluid and excretes the wastes out the side of the worm through the nephridiopore.
1. An earthworm has five hearts (also called aortic arches) that pump blood through their circulatory system.
2. The prostomium shovels dirt into the earthworm’s mouth. The food passes through the pharynx, the esophagus, the crop, the gizzard, and the intestine. It is excreted through the anus.
3. The ganglion in the anterior region. It is connected to the ventral nerve cord which runs the length of the worm.
4. The nephridia.
5. By cutting open any part of its digestive system (the intestine is probably the best) and examining the contents.
6. Since earthworms live on land, they need something to help them move along the earth. The setae are a useful adaptation because allow the earthworm to move easily by gripping the soil and allowing the worm to propel itself forwards.
7. The digestive system has specialized organs within it that allow the worm to absorb the small amount of food found in the dirt it ingests. The intestine is also large and has a lot of surface area to maximize the amount of nutrients that can be absorbed.
8. If we had have gone past segment 32, we would have seen identical segments. Within those segments would have been nephridia and the intestine.
9. The ectoderm develops into the skin and the nervous system, the endoderm develops into the digestive system (the intestine, the crop, and the gizzard), and the mesoderm develops into muscle and the remaining organ levels (the circulatory and reproductive systems). The muscle is attached to the skin and the digestive system with a cavity in between called the coelom.
10. The function of the nephridium is to filter the coelomic fluid. Coelomic fluid from the previous segment enters into the nephridium through the nephrostome. The nephridium filters out the good things in the coelomic fluid and excretes the wastes out the side of the worm through the nephridiopore.
11. Sandworm
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Earthworm
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12. Leeches have jaws that allow them to make incisions in their host’s skin and access their blood. They also have a sucker on the anterior and posterior regions.
Leech
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Earthworm
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phylum arthropoda
Characteristics
- coelomic
- protostome
- exoskeleton
- appendage formation
- bilateral symmetry
- triploblastic
- specialized segmentation
- respire through gills (aquatic), book lungs (arachnids), or tracheids (everything else)
- sexual reproduction
- open circulatory system
- body regions: head, thorax, abdomen
- ex. centipedes
- modified setae for movement
- specialized mouth appendages
- one pair of appendages per segment
- ex. millipedes
- unspecialized appendages
- two pairs of appendages per segment
- ex. crayfish
- mostly marine
- fused head and thorax called “cephalothorax”
- segments very specialized
- specialized appendages
- excellent sense organs
- ex. spiders
- fused cephalothorax
- four pairs of legs
- additional pair of mouth appendages
- book lungs
- no mandibles
- all predatory
- compose 65%-70% of entire animal kingdom
- three separate body regions (head, thorax, abdomen)
- three pairs of legs
- capable of flight
- tracheids (holes in abdomen allow them to breathe)
- excrete metabolic wastes through malpighian tubules
- vibration detecting timpanum
- ocelli between eyes
phylum arthropoda labs
Grasshopper Lab
Crayfish Lab
phylum echinodermata
Characteristics
- coelomic
- deuterostome (blastopore develops into the anus)
- exclusively marine
- semi-flexible endoskeleton (made of calcarious plates)
- reproduction is sexual but can regenerate limbs (seastars) or organs (sea cucumbers) if they are lost
- pentaradial symmetry (structures symmetrical in fives)
- water vascular system used for movement, feeding, and respiration
- external tube feet (part of the wvs) used for movement and hunting
- ex. seastars
- ex. sea urchins
- ex. sea cucumbers
- ex. sea lilies