BIO200-Annelids and Arthropods
Terms
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- Phylum Annelida
- 9000 species,evolved 570mya, proposed that they developed from an acoelomate flatworm ancestor.
- Class Polychaeta
- Clamworms
- Class Oligochaeta
- Earthworms
- Class Hirudinea
- Leeches
- Metamerism
- True segmental divison, external grooves, internal septa.
- Hydrostatic Skeleton
- body fluids act as support
- Cuticle
- on the surface of the annelid, a tough skin or cuticle with hard bristles
- Straight Digestive Tract
- A "more-or-less" straight digestive tract running from the mouth to the anus
- Closed Circulatory System
- blood is confined to vessels
- Segmented Nervous System
- nervous system consists of the brain (couple of big ganglia) and two ventral nerve cords with a pair of ganglia in each segment
- ganglia
- clumps of nervous tissue
- parapodia
- fleshy lobes for gas exchange; extended from body segments
- chaetae (setae)
- bristles on parapodia. these are used for locomotion
- pharynx
- first part of the digestive tract leading from the mouth
- esophagus
- tube leading from the mouth; opens in cardiac stomach
- stomach/intestine
- structure where digestion and absorption takes place. Found following the esophagus
- ventral nerve cord
- structure that transmists nerve impulses from above ganglia posteriorly along the inner ventral surface
- nephridia
- excretory system, (like tiny kidney tubes) one per segment
- gonochoristic
- seperate sexes, reproduce through copulation (physical act of mating)
- clitellum
- swollen glandular area that secretes a slimy material to form a cover for the eggs during reproduction
- Crop
- Thin-walled storage chamber for food recieved from esophagus
- Gizzard
- Muscular chamber that grinds the food; follows the crop
- Suprapharyngeal Ganglion
- A mass of nerve cells above the pharynx and connected by nerve chords and subpharygal ganglion below. Thus, the gut passes through the "brain"
- Pseuohearts
- five pairs of lateral blood vessels that are specialized to pump the blood
- Hermaphroditic
- have both male and female organs
- seminal vesicles
- aids in fertilization of the earthworm
- somites
- body segments, plainly visible in annelids. Inside the body the segments are separated by membranes called septa
- esophageal caecum
- secretes enzymes and increases surface area for digestion
- dorsal blood vessel
- structure through which blood flows anteriorly, found above the digestive tract
- ventral blood vessel
- structure through which blood flows posteriorly, found beneath the digestive tract
- Dorsal ganglion
- bilobed structure that coordinates nervous function. found in the prostomium; "the brain"
- Antennae
- (tentacles)...sense organs for touch and taste. found on the prostomium
- Cirri
- long bristles serving as organs of touch near the anus
- Lateral Vessels
- branched structures that supply each segment with blood. connect dorsal and ventral vessels in each segment
- Segmental Ganglion
- small masses of nerve cells in each segment which coordinate activities in each segment
- prostomium
- the first fleshy lobe of the head lying in front of the mouth. it has numerous sensory organs including eyes and tentacles or antennae
- Phylum Arthropoda
- 1 million species evolved at least 400mya
- Subphylum Trilobitomorpha
- trilobites...extinct
- Class Merostomata
- (xiphosurida)...horshoe crabs
- Class Eurypterida
- sea scorpions
- Class Arachnida
- spiders, scorpions, mites, etc.
- Subphylum Crustacea
- over 26,000 species, most found in class malacostraca
- Class Malacostraca
- crayfish, crabs, lobsters, shrimp, etc.
- Class Insecta
- (hexapoda)...grashoppers, bees, fruit flies, etc.
- Jointed Appendages
- arthro = jointed, poda = appendages...all arthropods possess jointed appendages adaptable to a variety of habitats
- Metamerism (arthropod)
- consists of a series of segments...each arthropod segment bairs a pari of appendages
- Regional Speciation
- groups of segments have fused together to form units called the head, thorax, and abdomen.
- Chitinous Exoskeleton
- a tough, horny inegument called chitin covers the arthropod. (exoskeleton!)
- Open Circulatory System
- blood flows from a heart and arteries into blood where it bathes tissue directly
- Sexual Dimorphism
- males and females have different body forms. (common in arthropods)
- carapace
- hard shell that covers the exterior of the chephalothorax
- antennae (arthropod)
- sensory organs for taste and touch; found dorsally at the anterior end of the cephalothorax
- chelipeds
- claws or pincers for feeding and fighting, underneath the carapace of the thorax; first pair of legs
- walking legs
- four pairs of legs used for locomotion; found underneath the carapace of the thorax
- swimmerets
- five pairs of appendages that aid in respiration and reproduction, found on the ventral side of the abdomen; sexually dimorphic; males' first pair is stiff and red; female swimmerets are all identical
- cardiac stomach
- structure with tiny calcified teeth used for grinding food; empties into the more posterior pyloric stomach
- pyloric stomach
- digestive chamber where further digestion takes place; empties into intestine
- intestine
- structure where absorption takes place; found following the stomach
- digestive gland
- secretes enzymes and absorbs food.
- gills
- feathery structures used in gas exchange, found under the carapace and rostrum
- heart
- structure that pumps the blood; found dorsally in the cephalothorax
- green glands
- paired glands taht secrete urine (in the form of ammonia) found in the head near the mouth
- gonads
- structures that produce gametes (testes or ovaries); found anterior to and slightly below the heart
- spiracles (arthropods)
- pairs of openings into the tubular gas exchange system along the sides of the animals; found on the last two subsections of the thorax and the first eight segments of the abdomen
- tympanum
- structure that serves as and ear drum; found on the first segment of the abdomen
- ovipositor
- structure responsible for laying eggs; the last three segments of the abdomen in females
- stomach
- structure where further digestion takes place; found following the crop
- cephalothorax
- the anterior rigid part of the 2 main sections of the crayfish
- abdomen
- posterior jointed part of the 2 main sections of the crayfish
- antennules
- smaller sensory organs for taste and touch; near the antennae
- mandible
- sturdy jaws, surrounding the mouth
- gastric caeca
- six double finger-shaped pouches connecting to the gut after the crop; secretes digestive enzymes and absorbs food
- thorax
- one of the three main sections of the grasshopper
- compound eyes
- complex light-sensitive sensory organs on the dorsal side of the head.
- ocelli
- three sensory organs that serve as simple eyes; between the compound eyes
- sensory palps
- slender structures used to feel and taste food
- trachae
- internal gas exchange feature of the grasshopper
- malpighian tubules
- many tubular structures that remove waste from the body fluids and empty them into the digestive tract and eventually out the anus
- cervical groove
- a tansverse groove on the carapace that separates the dorsal and ventral surface
- telson
- central flap of tail found at the end of the abdomen
- uropods
- side flaps on either side of the telson
- rostrum
- pointed structure of anterior end of the carapace; posterior to the antennae and antennules
- maxillae
- small, feathery appendages that manipulate food; directly cover the mandibles
- maxillipeds
- large appendages that manipulate food
- mandibular muscle
- muscle that controls the mandible
- supraesophageal ganglion
- structure that coordinates nervous function ("brain"); found above the esophagus in the head
- subesophageal ganglion
- coordinating center for mouth, esophagus, green glands and anterior muscles
- segmental ganglia
- ganglia found in each segment that transmits nerve impulses from nerve cord to the organs in that segment
- clypeus
- broad plate that is a protective structure over the mouth
- labrum
- broad upper lip hinged to clypeus which functions in eating