lecture exam 3

predation led to development of

shells, with larger shells allowing for more chambers and becoming buoyant

Phylum Mollusca synapomorphies

gills or “lungs,” open circulatory sys. (-cephalopods), heart and blood sinuses, metanephridia (kidneys), complete gut, radula, external or internal fert., monoecious or dioecious, trochophore or veliger larva

Phylum Mollusca members

Polyplacophora, Scaphopoda, Cephalopoda, Gastropoda, Bivalvia

radula

tongue-like organ with teeth rows, for feeding via scraping and drilling

Class Cephalopoda characteristics

present/reduced/lost shell, beak-like jaws, highly developed head and sensory organs, closed circulation, jet propulsion, lobed foot forming tentacles, no larval stage, male transfers spermatophore with specialized tentacles, female seals herself inside a den to care for eggs, she dies after they hatch

Class Gastropoda characteristics

• marine sp. undergo torsion

• freshwater + land sp. undergo detorsion

• sea hares have gills behind heart, form “mating chains,” emit ink clouds for protection, poisonous

• snails have gills in front of heart

torsion

180 twisting of visceral mass early in development (1st 90 occurs in veliger stage, 2nd 90 occurs later), results in anus and mantle over the head, one side of gills + kidneys + heart auricles stop working, enables waste disposal and reproduction

Class Bivalvia

• head-foot containing sensory organs + muscles

• visceral mass containing digestive, reproductive, circulatory organs

• mantle secretes the shell, forms cavity for gills/lungs

• morphology depends on environment

siphuncle

tube of tissue that goes through all septa in a shell, allows for making blood salty to bring in gas and increase buoyancy

Plectronoceras

first cephalopods, gas-filled chambered shell

Sphooceras

wrapped its mantle around its shell periodically to secrete enzymes to break off the end to make it more blunt and sturdy

Ammonites

grew quickly and had numerous offspring, wide variety of shell shapes and sizes

Coleoids

wrapped its mantle around its shell permanently, shell reduced to withstand deep sea pressure, only group to survive extinction event

Phylum Annelida synapomorphies

metameres, ladder-like nervous system with 2 cerebral ganglia + ventral nerve cord + 2 fused ganglia per metamere, longitudinal and circular muscles, chaetae, fluid in coelom acts as hydrostatic skeleton, gas exchange via diffusion, complete gut, crop + gizzard + intestine, prostomium and peristomium, closed circulation, sexual reproduction

metamerism

made up of repeating segments separated by septa but with organs running through

chaetae

chitinous bristles secreted by epidermis, used in locomotion and burrowing and gas exchange

prostomium

contains sensory cells, used as a feeding aid and acts as a plow blade for burrowing, protects mouth opening

peristomium

front lobe of mouth, first true segment, contains mouth opening

Phylum Annelida members

Polychaeta + Clitellata (Oligochaeta + Hirudinea)

Class Polychaeta

bristle worms. mostly marine, well-developed head with specialized sense organs, chaetae arranged in bundles on biramous parapodia, filter-feeding or predatory with jaws

Subclass Oligochaeta

earthworms. mostly aquatic or terrestrial, few setae, feed on detritus and have specialized digestive system to extract nutrients, monoecious and cross-fertilization via sperm exchange, clitellum, important soil aerators

Subclass Hirudinea

leeches. mostly freshwater, no septa or setae, 2 suckers for feeding and locomotion, some have proboscis or jaws, some are parasites of fish, monoecious and cross-fertilization via sperm exchange, salivary glands contain powerful anticoagulant

typhlosole

infoldings of dorsal side of intestine in Oligochaetes

clitellum

32-37 segments used for mucus secretion in mating, forming cocoon for eggs and sperm

Phylum Echinodermata synapomorphies

oral and aboral surfaces, pentamerous radial as adults and bilateral as larvae, calcareous endoskeleton derived from mesoderm, stereom, mutable collagenous connective tissue that can be softened/hardened at will or disintegrated due to stress or asexual reproduction, water vascular system, capable of regeneration, lack central nerve mass, can be sequential and simultaneous hermaphrodites, broadcast spawning, parental care, planktotrophic (feeding) or lecithotrophic (non-feeding) larvae

madreporite

AKA sieve, takes in water from aboral surface

tube feet

used for locomotion + collecting food and dissolved nutrients, works via hydraulic pressure and muscle action, water enters through radial canal ← ring canal ← stone canal ← madreporite

stereom

calcium carbonate material making up endoskeleton, hollow spaces are filled with tissue, individual pieces are ossicles

Phylum Echinodermata members

Subphylum Crinozoa (Crinoidea), Subphylum Asterozoa (Ophiuroidea, Asteroidea), Subphylum Echinozoa (Holothuroidea, Echinoidea)

Hemichordata

acorn worms. have distinct larval stage

Chordata synapomorphies

notochord, pharyngeal slits, endostyle/thyroid, dorsal hollow nerve cord, post anal tail. includes Cephalochordata, Urochordata, Vertebrata

Cephalochordata + Urochordata

Amphioxus + Tunicates. marine invertebrates, suspension feeders, collagenous support structures

Vertebrata

marine, terrestrial, freshwater vertebrates, jaws for feeding, skeletal support structures

importance of oligochaetes

bioindicators of soil health, control biomass and decomposing microorganisms, aerate soil and provide plants with nutrients

importance of phytoplankton

base of aquatic food webs, remove carbon from atmosphere

importance of chocolate midge

only cacao tree pollinator, found in rainforests

importance of cnidarians

provide habitats for marine life, absorb carbon, symbiotic with and control populations of algae

importance of termites

aerate soil and concentrate nutrients into mounds, abandoned mounds are habitats for other animals, help plants + fungi survive

importance of insecta

Dipterans are disease vectors, parasitoid wasps regulate other insect populations and can serve as biological pest control

importance of bivalves

mussels indicate pollution levels, tissue layers can indicate sea level and climate changes