Zoology Unit 3

What animals are in Phylum Arthropoda and what does Arthropoda mean?

Artho = joint; poda = foot

Spiders, mites, scorpions, insects, centipedes, millipedes, crabs, lobsters, shrimp, etc.

What kind of appendages does Phylum Arthropoda have?

Paired, jointed appendages often modified for various functions

Uniramous

Appendage ends in single segmented section (Arthropoda)

Biramous

Appendage ends in paired segmented sections (Arthropoda)

Chelate

Appendage ends in hinged pincher or claw (Arthropoda)

Chelicerae

Segmented mouthpart. Found with 2nd pair of segmented mouthparts called PEDIPALPS; highly modified (Arthropoda)

Mandible

Reinforced, unsegmented mouthpart for crushing food. Found with 1 or more pairs of segmented mouthparts called MAXILLA (Arthropoda)

What is the exoskeleton of arthropods made of?

The cuticle is reinforced by chitin (polysaccharide) and sometimes calcium salts; molted for growth (ecdysis)

What are some general characteristics of arthropods?

1. Bilateral
2. Protostomes
3. Triploblastic
4. Metameric
5. Tagmatization (specialization of segmented body regions - tagma)

What are arthopods coelom like?

Reduced coelom with an open circulatory system and open body cavity called a HEMOCOEL

Is metamorphism present in arthropods?

Yes; Larval stage often looks different from adult

What are the 6 reasons for arthropods being the most diverse and successful animal group?

1. Versatile exoskeleton - Tough, lightweight, flexible, sheds
2. Metamerism/tagmatization - Body segments can be specialized
3. Efficient respiration - Possess TRACHEA (Tubelike network for gas exchange in each metamere)
4. Highly developed sensory organs
5. Complex behavior (socially and colonially)
6. Metamorphism - Larval form and adult utilize different ecological niches rather than compete

Subphylum Trilobita

Extinct trilobites; 600-250 m.y.a. were the dominant marine life forms; scavengers (Arthropoda)

Morphology of trilobites

1. Flattened, oval body with 3 longitudinal lobes (axial plus 2 pleural) and 3 tagmata (head, trunk, pygidium)
2. Appendages were biramous
3. 1 pair of antenna but no mouthparts
4. Mouth called HYPOSTOME

(Arthropoda)

What is the morphology of subphylum chelicerata?

1. 2 tagmata: Cephalothorax (prosoma) and abdomen (opisthosoma)
2. 6 pairs of appendages located on cephalothorax

(Arthropoda)

What are the 6 pairs of appendages located on the cephalothorax of subphylum chelicerata?

1. 1st pair called chelicerae: used for feeding; can be chelate
2. 2nd pair are pedipalps: function varies; can be chelate
3. Usually 4 pairs of walking legs (8 total)
4. No mandibles or antennae

(Arthropoda)

What animals are in class merostomata and the body structure?

Horseshoe crabs and giant water scorpions (extinct)


1. Hard, shell like carapace over cephalothorax
2. Chelicerae, pedipalps, and first 3 pairs of legs are chelate
3. Long Telson (tail-like structure) and book gills on abdomen

(Arthropoda)

How many living species of horseshoe crabs are there and where are they located? What do they feed on?

5 living species only in the Atlantic Ocean; feed on soft worms and small molluscs (Arthropoda)

What are sea scorpions?

1. Largest arthropods to ever exist (up to 9 ft. long)
2. Scavengers/predaceous on smaller animals
3. Extinct about 200 m.y.a.
4. Share traits with horseshoe crabs and modern terrestrial scorpions

Malpighian Tubules

Numerous thin filaments in the abdomen that absorb excretory wastes from body cavity and empty into gut (Class Arachnida; Order Araneae; Hexapoda)

Coxal Glands

In cephalothorax that are nephridia that dump waste near coxa (first section of legs) (Class Arachnida; Order Araneae)

Book Lungs

Pairs of invaginations of ventral body wall form thin folds called LAMELLAE where air circulates for gas exchange (Class Arachnida; Order Araneae)

Morphology of class arachnida order araneae

1. Chelicerae function as fangs with ducts to venom glands
2. Predaceous
3. Pedipalps are large and leg-like
4. Usually 8 eyes but vision isn’t great
5. Abdominal silk glands produce liquid protein that exits body through SPINNERETS to make silk; threads stronger than threads of same diameter

What animals are in class arachnida order araneae?

Spiders; no external segmentation on tagma that are joined by narrow PEDICEL

What are the 2 species of spiders that are concerning in Oklahoma?

1. Lactrodectus mactans: Black Widow - produces neurotoxin that attacks nervous system (5/1000 bites are fatal
2. Loxosceles reclusa: Brown Recluse - produces hematoxin that destroys tissue near bite. Rarely fatal

What animals are in class arachnida order scorpionida? What is the morphology like?

Scorpions


1. Jawlike chelicerae with large chelate pedipalps
2. Predaceous
3. Subdivided abdomen

a. Preabdomen: Contains book lungs and genital openings

b. Postabdomen: Narrowed with bulbous stinger

What animals are in class arachnida order opiliones? What is the morphology like?

Harvestmen “Daddy Longlegs”


1. Prosoma joins abdomen broadly - body appears oval
2. Predators/omnivores
3. Feed on aphids; good pest control

What animals are in class arachnida order acari? What is the morphology like?

Mites and ticks


1. Ectoparasites on vertebrates; other scavenge
2. Cephalothorax and abdomen fused with single carapace
3. Anterior projection called CAPITULUM has mouthparts
4. Chelicerae and pedipalps used for piercing, anchoring, biting, sucking

What are some examples of class arachnida order acari?

1. Trombicula: Common mite (red bug). Larvae (chiggers) digest and feed on vertebrate skin. Birds are main host. Usually not fatal due to larvae being easily removable. Repelled by DEET.
2. Demodex: Found in human hair follicles (eyebrows especially). Amount increases with age. 20% in those 20 or younger, 100% in elderly. Some infect animals; mange
3. Sarcoptes mite: Cause Sarcoptic mange in animals or Scabies in people bu tunneling under skin as they feed

Ticks

1. Ectoparasites
2. Major vectors of Lyme disease, RMSF, Ehrlichiosis, tularemia, etc
3. 2nd biggest vector of human disease behind mosquitoes
4. Females engorge with blood and lay eggs; eggs hatch 6 legged seed ticks
5. Molt several times before adulthood
6. Class Arachnida Order Acari

Subphylum Myriapoda

1. 2 tagmata - head and trunk
2. Uniramous paired appendages on most segments
3. 1 pair of antennae and mandibles; 1-2 pairs maxillae

(Arthropoda)

What is the morphology of class chilopoda?

1. A few to 177 segments in flattened body
2. 1 pair of legs per segment except first segment which has MAXILLIPEDS with poison fangs
3. Last pair of appendages called CERCI; used for reproduction and courtship, threat display
4. Add segments at each molt

(Arthropoda)

What animals are in class chilopoda?

Centipedes; fast predators but bite is usually worse than toxins to humans (except some tropical species) (Arthropoda)

What is the morphology of class diplopoda?

1. 25-100 segments in oval body
2. 1 pair of legs on 4 thoracic segments, but 2 pairs of legs per abdominal segment. Larvae have 1 pair of legs per segment

(Arthropoda)

How are the “segments” of class diplopoda formed? What animals are in class diplopoda? What are their habits?

Millipedes


1. Segments formed from fusion of 2 embryological metameres so they are called DIPLOSEGMENTS

Habits: Worldwide distribution in moist soils, scavenge on decaying vegetation; many can release hydrogen cyanide from REPUGNATORIAL GLANDS

(Arthropoda)

Morphology of subphylum crustacea

1. 2 pairs of sensory antennae; predominantly aquatic; mostly marine
2. Numerous biramous appendages (chelate as well)
3. Dorsal cuticle extends down and back to form carapace
4. Tagma: highly variable although most with a cephalothorax and abdomen; some forms have separate head, thorax, and abdomen

(Arthropoda)

Antennal glands

Used for excretion and osmoregulation; green glands in decapods (Arthropoda)

Class Oligostraca

1. Usually 15 segments in body plus telson; unique eyes if present; variable carapace
2. Subclass Ostracoda: Ostracods; covered by bivalve carapace - resemble clams, reduced appendages, scavenge/burrow in aquatic sediments

(Arthropoda)

Characteristics of class vericrustacea subclass branchiopoda

1. Very small 1st antennae; flattened, leaf-like legs, variable carapce
2. Order anostroca: Fairy and brine shrimp; lack carapace
3. Order diplostraca: Water fleas; carapace covers body but not head; Daphnia common freshwater group

(Arthropoda)

Characteristics of class vericrustacea subclass copepoda

1. Copepods
2. Lack carapace
3. Elongated and tapered body
4. Single median eye in some species
5. 4 pairs of large thoracic appendages
6. No abdominal appendages
7. Planktonic/benthic habitats
8. Cyclops (species)

(Arthropoda)

Characteristics of class vericrustacea subclass thecostraca

1. Barnacles
2. Carapace usually surrounds body & secretes calcareous shell
3. No abdomen
4. Thoracic legs covered with setae for filter feeding

(Arthropoda)

What animals are in subclass malacostraca? What is the morphology like?

Crabs, lobster, shrimp, etc.


1. 2 part body - cephalothorax and muscular abdomen
2. Numerous paired appendages (some robust & chelate)
3. Order DECAPODA: Crabs, lobsters, shrimp, crayfish

a. 5 pairs of walking legs, 1st pair usually chelate

b. Many abdominal appendages

c. Crabs have reduced abdomen


4. Order ISOPODA: Pillbugs or “rollypollies”

a. No carapace

b. Compound eyes

c. Abdominal appendages bear gills

d. Terrestrial and aquatic forms; some parasitic to fish


5. Order AMPHIPODA: Beach fleas

a. No carapace

b. Laterally compressed

c. *Gammarus* common freshwater group

(Arthropoda)

How many named species of plants, fungi, animals, and microbes are there? What number are insects? Beetles?

1\.5 million; 1 million are insects (67%) and 350k are beetles (23%)

What do insects do for terrestrial ecosystems?

1. Pollination
2. Decomposition
3. Nutrient cycling

Entomology

Study of insects; since insects are so important, many universities have entomology departments devoted to study and control of locally important insects and arthropods

What are some diseases that insects can transmit to people?

malaria, Zika, West Nile virus, filarial worms, Chagas disease, plague, typhoid, typhus, African sleeping sickness, yellow fever, Dengue fever, etc.

Do we compete with insects for food?

Yes

What are examples of harmful insects?

Grasshoppers, mosquitoes, cinch bugs, corn borers, boll weevils, grain weevils, scales, bark beetles, budworms, cockroaches, gypsy moths, Lice, warble flies, bot flies, horseflies, fleas, some ants (Fire Ants), bed bugs, termites, carpet beetles, clothes moths, Japanese beetles, etc.

What are 3 good ecological services insects provide?

1. Insect pollination, pest control, and wildlife food webs generate $57 billion in benefits in the US annually
2. Domesticated bees pollinate $15 billion worth of crops annually in the US
3. Useful products: Beeswax, honey, silk, and shellac

How many insects are declining from environmental factors? What are these environmental factors?

40%; Climate change, pesticide abuse, habitat loss and urbanization, and invasive species

What was the Colony Collapse Disorder in 2006?

1. Infection by a virus called “deformed wing virus” endemic to Varroa mites would infect developing worker bees which would cause them to fly away and die (no workers means no colony)
2. Other studies believe neonicotinamide insecticides could have been a cause

Biology of subphylum Hexapoda class insecta

1. Uniramous paired appendages on some segments; 1 per antennae
2. 3 pairs of walking legs (6 total) on thoracic segments
3. 0-2 pairs of wings on thorax
4. Metamorphic with larvae often occupying different habitats than adults
5. Social and colonial in some orders with complex behavior

Morphology of subphylum hexapoda class insecta

1. 3 tagmata

a. Head: 1 pair antennae, mouthparts, compound eyes

b. Thorax: 3 segments partially fused

\-Prothorax: 1 pair of legs

\-Mesothorax: 1 pair of legs & often 1 pair of wings

\-Metathorax: 1 pair of legs & often 1 pair of wings

c. Abdomen: 10-11 segments; contains reproductive structures & organs, some digestive


2. 1 pair mandibles but often modified into diverse mouthparts for biting, chewing, sucking, etc.

What is the digestive system of subphylum hexapoda class insecta like?

1. Foregut: Mouth, esophagus, crop
2. Midgut: Gastric Ceca - Blind pouches that produce enzymes
3. Hindgut: Intestine, colon, & rectum

Excretion in subphylum hexapoda class insecta

Malpighian tubules collect waste and dump it into the gut at the midgut/hindgut boundary

Circulation in subphylum hexapoda class insecta

1. Open body cavity called hemocoel filled with fluid called hemolymph that is moved by weak dorsal heart
2. Most circulation incidental from body movements

Respiration in subphylum hexapoda class insecta

Tracheal system brings air almost directly to every cell in body

Ametabolous metamorphosis

Adults and young (larvae) very similar and only differ in size and sexual maturity. Only in primitive wingless insects (Hexapoda)

Paurometabolous

Adults and young (nymphs) differ in that adults have fully developed wings & are sexually mature; occupy same habitats; nymphs gradually molt into adults (grasshoppers, true bugs) (Hexapoda)

Hemimetabolous

Adults and young (naiads) differ because naiads are aquatic, adults are not (dragonflies, mayflies) (Hexapoda)

Holometabolous

Adults and larvae quite different (higher insects: beetles, butterflies, wasps, ants, etc.) with 4 stages of development


1. Egg
2. Larvae
3. Pupae
4. Adult

(Hexapoda)

What are the 10 major familiar groups of insects?

1. Order ODONATA: dragonflies and damselflies.
2. Order ORTHOPTERA: grasshoppers, crickets.
3. Order ISOPTERA: termites.
4. Order PHTHIRAPTERA: lice.
5. Order HEMIPTERA: stinkbugs, planthoppers, cicadas.
6. Order COLEOPTERA: beetles.
7. Order LEPIDOPTERA: butterflies and moths.
8. Order DIPTERA: flies, gnats, mosquitoes.
9. Order SIPHONAPTERA: fleas
10. Order HYMENOPTERA: ants, bees and wasps.

Be familiar with Hexapoda Slide 17

What is the breakdown of the word echinodermata?

echino = spine; dermata = skin

What is the body structure of phylum echinodermata?

1. Coelomate deuterstome development
2. Calcareous endoskeleton arising from mesodermal germ layer

a. Ossicles - Calcium carbonate plates

b. Spines - Fixed/movable; usually project through skin


3. Pentaradial symmetry; 5 arms (ambulacra) means no 2 joints of the skeleton are directly in with each other

Tripartite coelom

Bilateral larvae develop into pentaradial/bilateral adults with this coelom.


1. Oral/aboral coleom
2. Water vascular system
3. Heme system

(Echinodermata; slide 4 pics)

What is the internal water vascular system of phylum echinodermata consist of?

Basis of locomotion and food gathering systems


1. Madreporite - Opening to system. Lets water in & out
2. Stone Canal - Connects madreporite to water vascular system
3. Ring Canal - Centralized dispersal structure
4. Radial Canal - Runs down center of each arm; to lateral canals
5. Ampulla - Internal bulb fills and deflates to operate TUBE FEET: external sucker pads used in locomotion and feeding

What is the digestive tract and nervous system of phylum echinodermata like?

1. Complete that has been secondarily reduced in size and complexity
2. Some groups, intestine and anal opening are lost
3. No head/brain; basic nervous system

How many classes are in phylum echinodermata? How many survive today?

20; 5

What animals are in class asteroidea? General characteristics of class asteroidea

Starfish


1. Common, adbundant marine forms
2. Predaceous, many feed on bivalves/echinoderms
3. Regenerate new body parts from pieces of central disk (autotomy)

(Echinodermata)

How does class asteroidea feed?

1. Evertable stomach (CARDIAC stomach) that digests bivalves in shell. Holds bivalve under pressure until tires then stomach and digestive fluids are inserted
2. Sucks up into branching digestive organs in each arm (PYLORIC CAECA) for digestion

(Echinodermata)

Pedicellariae + example

Tiny, pincher-like structures used for defense, keep surface clean, and sometimes in prey capture

Common species in Pacific NW called “Velcro starfish” captures snails, chitons, etc.

(Echinodermata)

Class Ophiuroidea

Brittle stars and basket stars


1. Arms distinctly set off from central disk
2. No pedicellarae
3. Tube feet have no suckers
4. No intestine/anus (secondarily derived 1 way gut)
5. Long arms may be highly branched

(Echinodermata)

Class Echinoidea

Sea urchins and sand dollars


1. Endoskeletal shell called a TEST
2. Sea urchins: Round/globular; 10 ossicles make up test; movable spines often filled with toxins
3. Sand dollars: Flat/mounded; small spines; burrow in mud
4. Graze on coral & other immobile creatures; scavenge

(Echinodermata)

Class Holothuroidea

Sea cucumbers


1. No arms; lie on 1 particular side called the SOLE
2. Secondary bilateral symmetry
3. No protruding spines
4. 3 rows of tube feet on sole for movement
5. Sluggish, slow moving scavengers

(Echinodermata)

Class Crinoidea

Sea lilies and feather stars


1. Most primitive; oldest living group
2. Sea lilies: Stalked with disk-like ossicles; body called the CROWN; highly branched arms for filter feeding; stalks common in limestone fossils beds in OK
3. Feather stars: No stalk; swim & crawl on bottom; scavenge

(Echinodermata)

What 5 traits are present at some point in Phylum Chordata’s life?

1. Notochord: Skeletal rod made of cartilage
2. Dorsal Hollow Nerve
3. Pharyngeal Pounches/Gill Slits
4. Endostyle/Thyroid Gland
5. Postanal Tail

What level of tissue is the notochord developed from? What does it turn into later in life?

1. Mesoderm
2. Retained sometimes in chordates, in vertebrates it is partially replaced by vertebrae, pieces are retained in mammals as intervertebral discs

(Chordata)

What tissue does the dorsal hollow nerve chord develop from? What does it turn into?

1. Ectodermal infolding
2. Anterior end enlarges to from brain in many chordates

(Chordata)

What tissue are the pharyngeal pouches/gill slits developed from? What does it turn into?

1. Ectoderm folding in and endoderm folding out
2. If body wall is perforated, forms slits used as filter feeding devices for water exit in lower level chordates
3. Thin-walled capillary beds w/ high surface area for gas exchange is added to this structure, it forms gills

(Chordata)

What tissue does the endostyle/thyroid gland form from? What does it do?

1. Endoderm
2. In lower vertebrates it secretes iodine-rich mucous to trap particles during feeding
3. In vertebrates it secretes iodine-rich hormones as thyroid gland

(Chordata)

What tissue is the postanal tail formed from? What are some other characteristics of it?

1. Mostly by mesoderm
2. Coupled with myomeres (segmented muscle attached to notochord for propulsion)
3. Fish later developed fins from fold in body wall + limbs for stabalizing

(Chordata)

What are some other general chordate traits?

1. Deuterostome development with well-developed coelom
2. Bilateral symmetry with complete digestive tract
3. Metameric: segmentation, if present, only on outer body wall and not into coelom

(Chordata)

What animals are in subphylum urochordata? What are some general characteristics of young?

Tunicates or Sea Squirts


1. Sessile, sac-like, filter feeding adults (mostly)
2. Fish-like, free-swimming larvae (mostly)
3. Larvae metamorphosis into adult form; loses notochord, nerve cord to an extent

(Chordata)

What are characteristics of the adult body of subphylum urochordata?

1. Has a large atrium (hollow area) in body
2. Large pharynx perforated for filtering
3. Food particles gathered by ciliated, mucous-covered endostyle
4. Moved into stomach then intestine
5. Monoecious; gametes shed externally into atrium

(Chordata)

What phylum and subphylum are salps a part of?

Form of free-floating colonial tunicates


1. Phylum Chordata; Subphylum Urochordata

What animals are in subphylum cephalochordata? What are some general characteristics?

Lancelets


1. Elongate, laterally flattened tadpole-like filter feeders
2. Poor cephalic development
3. 32 spp. worldwide, 5 along the sandy shores of North America
4. Retain all 5 chordate characters throughout life

(Chordata)

What are the key anatomical features of subphylum cephalochordata?

1. Oral hood: Bears cirri (ciliated projections) for filtering sand particles from water
2. Large perforated pharynx with internal endostyle; all supported by gill arches made of cartilage
3. Long atrium created by folds of body wall; After passing through pharynx, water exists through atriopore
4. Dioecious; gametes shed into atrium then out to water

(Chordata)

What 2 common traits of vertebrates does subphylum cephalochordata possess?

1. Myomeres (segmented bands of muscle)
2. HEPATIC CECUM: where food particles are digested (modified into the LIVER in vertebrates)

(Chordata)

What was the notochord replaced by in subphylum vertebrata?

Replaced by disclike CENTRA with projections for muscle attachment

(Chordata)

What was the notochord in subphylum vertebrata originally formed of and what was it replaced by?

1. Initially formed of cartilage
2. Replaced by bone in many by infusing cartilage w/ collagen and hydroxyapatite (mineralized material made from calcium and phosphate)

(Chordata)

Ostracoderms

Bone used in skin for making protective plates as seen in earliest known vertebrates (Chordata; Sub Vertebrata)

Early vertebrates were much larger and more mobile than protochordates due to changes in the skeleton and muscles (T/F)

True

What are some physiological upgrades of subphylum vertebrata?

1. More active lifestyle requires more oxygen and fuel
2. Vascularized gills were developed along the pharyngeal arches
3. Hearts were better developed to move blood
4. Liver and pancreas added to increase digestive efficiency
5. Predation eventually replaced filter feeding; requires better senses and larger brain; organs need protection, cephalization increases and bony case added around brain (Cranium)

(Chordata)

What are somee examples of subphylum vertebrata?

1. Pikaia: Found in the middle-Cambrian Burgess Shale of Canada. Lack of distinctive cephalization indicates probably another Cephalochordate
2. *Haikouella*: found in the early-Cambrian fossil beds of Haiku, China. Lack of cranium indicates probably a sister group to the vertebrate ancestors

(Chordata)

What are 2 structures of early paleontology of vertebrates?

1. CONODONTS: very early forms much like a lancelet but with better head development and eyes
2. OSTRACODERMS: 1st true vertebrates; armored jawless fishes common in fossil record. Good cephalization; bony plates in skin

(Chordata)

What are the 2 anatomical transformations of placoderms?

1. 2 pharyngeal arches repositioned and extended around mouth to form JAWS
2. Folds of body wall were used to develop stabilizing fins. Later on, skeletal and muscle additions allowed fins to be strengthened and controllable

(Chordata)

Agnatha, gnathostomata, pisces, tetrapod, anamniota, amniotes definitions

AGNATHA: without jaws.

GNATHOSTOMATA: jawed mouths.

PISCES: fish

TETRAPOD: 4 legged terrestrial animals.

ANAMNIOTA: non-amniote vertebrates – no extraembryonic membranes.

AMNIOTES: vertebrates with extraembryonic membranes.

What distinctive features set apart Subphylum Vertebrata (Craniata) from other chordates?

1. Basic chordate features + distinctive cartilaginous or bony ENDOSKELETON with the notochord replaced by serial CENTRA that form VERTEBRAE
2. All have a bony CRANIUM around highly developed BRAIN. Vertebral column and cranium form AXIAL SKELETON..

(Chordata; Fish)

What are some general characteristics of Subphylum Vertebrata (Craniata)?

1. Muscularized and differentiated digestive system
2. Ventral heart with multiple chambers as part of a closed circulatory system
3. Excretory system with paired, glomerular kidneys
4. Endocrine system
5. Most with 2 pair of appendages supported by LIMB GIRDLES and APPENDICULAR SKELETON that is supplemental to AXIAL SKELETON

(Chordata; Fish)