Bio 108 Exam 3 Review

define coelom

air/fluid filled space between the digestive tract and endoderm

define coelomates

organisms with true coelom that arose from the mesoderm

define pseudocoelomates

organisms with coelom that formed from both the mesoderm and ectoderm

define acoelomates

organisms without coelom

define radial symmetry

organisms with radial symmetry are symmetrical around a central axis, with no distinct head or tail

define bilateral symmetry

organisms that are bilaterally symmetrical can be divided into two halves along one plane

define diploblastic

diploblastic organisms only have an ectoderm and endoderm

define triploblastic

triploblastic organisms have an ectoderm, endoderm, and a mesoderm

define ectoderm

the ectoderm is a germ layer that surround the zygote and will give rise to the skin/outer layer of the organism, and sometimes even the central nervous system

define endoderm

the endoderm is the innermost germ layer that will give rise to the digestive tract

define mesoderm

the mesoderm is an additional germ layer that will form muscles and organs in between the ectoderm and endoderm

define filter feeders as it pertains to sponges

sponges are considered filter feeders because they are sedentary organisms attached to a substrate that draw water into their bodies to then consume any food particles and nutrients that come in

define ameobocytes

sponges have ameobocytes which are cells that absorb and transport nutrients around the sponge. they also act as reproductive cells, jelly-secreting cells, and they produce calcium carbonate skeletal fibers and spongin proteins. because they specialize in so many things they are considered totipotent

define a sponge’s osculum

the osculum is the big hole in the top of a sponge that the water leaves out of during the filter feeding process

define choanocytes

sponge’s have choanocytes which are organisms that line the inside of the sponge and have flagellated collars that assist in drawing water in for filter feeding

define a sponge’s spongocoel

the spongocoel is the central cavity of the sponge where the choanocytes & amoebocytes are located, and where water is drawn into during filter feeding

define a sponge’s spicules

spicules are spine-like skeletal structures that are the main identifier of sponges. they are made of silica, spongin, or calcium carbonate.

define a sponge’s incurrent pores/ostia

the outer layer of a sponge consists of many pores called ostia which are the entry doors for water during the filter feeding process

define a sponge’s gemmules

gemmules are clusters of amoebocytes enclosed in hard shells that are capable of withstanding adverse conditions and are used during asexual reproduction of the sponge. (sponges also do asexual reproduction via budding or fragmentation)

define hermaphroditic

sponges are hermaphroditic which means they begin as one sex, produce gametes, and then switch sexes to engage in sexual reproduction

define a cnidaria’s bud

the cnidaria use buds during asexual reproduction, which are essentially just smaller versions of the original organism. these will grow on the main body before breaking off and starting a completely new organism

define cnidocytes

cnidocytes are stinging cells located on the tentacles of cnidaria

define nematocysts

nematocysts are barbed cells located on cnidocytes that when triggered (unconsciously) will explode out and sting the prey

define cnidaria’s polyps

polyps are a classification of cnidaria who sit, sedentarily, on a substrate with their tentacles pointed upward

define a cnidaria’s medusa

a medusa is a classification of cnidaria who are mobile and swim with their tentacles pointed downward

define a cnidaria’s gastrovascular cavity

the gastrovascular cavity is the area in which cnidarians perform extracellular digestion. there is only one opening to the gastrovascular cavity, called the mouth/anus

define a cnidaria’s basal disk

basal disks are exclusively found on hydras and are located at the bottom of the organism. they secrete a sticky substance that allows the hydra to attach to a substrate

define the cnidaria’s epidermis

the epidermis of a cnidaria is their external tissue

define the cnidaria’s gastrodermis

the gastrodermis of a cnidaria is the internal tissue

define the cnidaria’s mesoglea

the mesoglea of a cnidaria is the jelly-like matrix within the middle of the organism

define Anthrozoa

Anthrozoa refers to sea anemones and corals. sea anemones are often colorful, have hundreds of tentacles that wave with the currents, and feed mainly on fish that are paralyzed by the tentacles. corals are smaller than sea anemones and live in colonies. they are composed of the skeletons of cnidarians that have built up over many years. they form reefs which are home to many other oceanic organisms

define Sphycozoa

Sphycozoa refer to jellyfish. these organisms move freely throughout the ocean and obtain their food by capturing small animals with their tentacles

define Hydrozoa

Hydrozoa refers to hydras. these are normally freshwater organisms and are large enough to be seen with the naked eye, but can been seen with greater detail under microscopes. they have 5-6 tentacles surrounding their mouth, each with individual bumps that mark the locations of the cnidocytes. hydras move by floating and also perform cartwheels where they flip over onto their tentacles and then regain their original orientation

what do cnidarians have instead of a brain

cnidarians have a nerve net that coordinates their movements and responds to their environment

define the head of a flatworm

flatworms have an identifiable head (making them bilaterally symmetrical) which contains all of its sensory structures

define the organ systems of a flatworm

flatworms are triploblastic, meaning their mesoderm formed in to organs that allows the organism to have several, well-developed organ system

define Turbellaria

Turbllaria refers to the free-living flatworms. these organisms are considered free-living because they are not parasitic. they also have an unusually located mouth (protrusible pharynx in the middle of the body) and a ciliated epidermis that aids in locomotion. they are simple animals, but have a brain and CNS, a well-developed excretory system, and a complex reproductive system

define Planaria

Planaria are a genus of Turbellarian. they have simple eyes that are light receptors only and do not allow them to form images. they also have lateral projections on their head called auricles which function as sensory lobes with both touch and chemical receptors. they also have ganglion centered in the head, with one nerve cord running the length of their body

define Trematoda

Trematoda (aka Flukes) refers to flatworms that are internal parasites. they have an oral sucker on the anterior end for attachment to the host, which they will use to feed on blood. they also have a complex hermaphroditic reproductive system (can see both testes and ovaries in a mounted specimen). they can reproduce quickly and effectively because their larval stages can reproduce asexually. flukes initially live in intermediate hosts that harbor the asexual parasites (oftentimes molluscs) before they move onto their final host (a vertebrate) which is where the fluke will engage in sexual reproduction and spend the remainder of its life.

define Cestoda

Cestoda (aka tapeworms) are another type of internally parasitic flatworms. their adult form will live in the intestine of a vertebrate and absorb the nutrients that have already been digested by the host. tapeworms do not have a digestive system of their own, but do have a specialized epidermis to assist them in resisting the host’s digestive enzymes. tapeworms tend to be host-specific and can only reproduce in certain hosts. they also have a life cycle with both intermediate and final hosts. tapeworms are segmented, with a narrow, ‘head’, end that contains a scolex. the scolex has hooks and suckers that are used to attach to the host. each segment after the head is referred to a proglottid, all of which are reproductive machines containing both female and male sex organs. once proglottids have matured to contain hundreds of fertilized eggs, they become ‘gravid’ and break off to be passed out of the host’s digestive system

define a nematode’s cuticle

the cuticle is the outer layer of a nematode that is flexible and nonliving and is made primarily of collagen

define a nematode’s epidermal cords

epidermal cords are sections of a nematode that separate the groups of longitudinal and circular muscles in the roundworm

define Ascaris

Ascaris refers to the human intestinal roundworm. this species is parasitic and are present in their hosts in great numbers, and are all pseudocoelomates. these round worms do not have respiratory or circulatory organs. Oxygen is obtained via breaking down glycogen and circulation occurs in the pseudocoelomic fluid. females tend to be larger than males, and males are identifiable by their curved posterior end, and two chitinous spicules projecting from the anal region. spicules are used during mating in order to attach to and widen the female’s vulva for sperm transfer. the male’s anus discharges both feces and sperm

define a nematode’s pharynx and intestine

in a nematode, the pharynx follows the mouth and sucks food into the ribbon-like intestine. the intestine are very thin to allow for food absorption into the pseudocoel

explain the female reproductive system of roundworms

in roundworms, most of the pseudocoel contains the female reproductive system. it is a y-shaped set of long, convoluted tubes; the base of which is the vagina that opens to the outside at the vulva. the long arms of the ‘y’ are the uteri, which extend posteriorly and then double back as slender oviducts, which connect the uteri with threadlike ovaries. eggs pass from ovaries to oviducts to uteri where fertilization will eventually occur and shells will be secreted from. the uteri can contain 27 million eggs at a time, and 200,000 eggs can be laid in a daye

explain the male reproductive system of roundworms

in roundworms, the male reproductive system is a singular, long tube that is made of coiled, threadlike testes, which contain thicker vas deferens. the vas deferens will connects to the wider seminal vesicle which empties into a short, muscular ejaculatory duct into the anus. during sex, spermatozoa will exit through the ejaculatory duct into the vagina

define a mollusc’s hemocoel

in a mollusc, the hemocoel is the small space around the heart where the coelom is reduced

define a mollusc’s mantle

the mantle is a tissue that lays over the mollusc’s visceral mass and secrete’s the organism’s hard calcium carbonate shell

define a mollusc’s mantle cavity

the mantle cavity in a mollusc is a small space between the mantle and the visceral mass. the mantle cavity houses the gills, anus, and excretory pores

define a mollusc’s gills

a mollusc’s gills are highly complex, folded sheets of tissue that are used to exchange oxygen and carbon dioxide during respiration. in bivalves, gills are enlarged and can also be used for filter feeding

define a mollusc’s radula

a radula is a tiny, chainsaw-like structure made of chitin that molluscs use to scrape food

define a mollusc’s visceral mass

molluscs have visceral mass that is a solid mass of tissue with all of the organism’s internal organs embedded within

define a mollusc’s foot

molluscs have a muscular foot which protrudes from the bottom of the organism and can be used to dig in the sand (bivalves), creep along rocks (gastropods), or it can be divided into tentacles to capture prey (cephalopods)

explain a mollusc’s circulatory system

molluscs have an open circulatory system where only part of the blood flow is contained in vessels. the heart will collect oxygenated blood from the gills and forces it into small vessels which reach the tissues directly. the blood will also pool in small chambers/sinuses where it is collected and carried back to the gills

explain a mollusc’s excretory system

molluscs have a well developed excretory system which organize tubular nephridia into kidneys. these kidneys will collect liquid waste from the coelom and dump them into the mantle cavity where they will be pumped out of the shell

what types of molluscs are hermaphroditic

bivalves and some snail species are hermaphroditic, while all other molluscs are dioecious

explain a molluscs’s nervous system

molluscs have a pair of ganglia and nerve cords that have statocysts, which act as balance organs. they also have eyes as major sense organs

define Polyplacophora

Polyplacophora (chitons) are soft organisms with a simple ‘tube in a tube’ body plan that is protected by a shell of 8 overlapping calcium carbonate plates. their bodies are dorsoventrally flattened and they feed via their radula

define Bivalvia

Bivalves (mussels, clams, oysters, scallops) are laterally flattened organisms whose body is enclosed between two shells that open via a hinge ligament, and are held closed via strong adductor muscles. bivalves form a pair of siphons (incurrent and excurrent) which let water in and out, respectively. the flow of water is caused by movement of the cilia that covers the gills. this flow brings in oxygen, food, and gametes while carrying away waste materials. bivalves are all sedentary filter feeders, and can catch food thanks to a coating of mucus on their gills. bivalves also have mobile trochophore larvae that allow for wide dispersal of bivalves

define Gastropoda

Gastropods (snails, slugs, limpets, conchs, whelks, abalones) are defined by their spiral twisting body plans. this results from one side of the larva growing faster than the other in early development. the twisting of the organism’s shell is secondary to the twisting of the organism’s body. gastropods can withdraw into their shells, leaving only a single opening to defend which is capped by a shelly plate called the operculum. gastropods do not have any organs on their right side due to the twisting and the anus is brought to a position right above the organism’s head. most gastropods have a pair of sensory tentacles on their heads, which have primitive eye spots on the ends. some predatory species have even modified their radula to drill into other organisms

define Cephalopoda

Cephalopoda (octopi, squid) are marine predators that use their tentacles (modified foot), which have large sucker disks to grasp prey and bring it to their mouths, which are beak-like and contain poisonous saliva. male cephalopods will also use their tentacles to place sperm in a female’s mantle cavity during reproduction. cephalopods are also the only molluscs that have entirely closed circulatory systems. cephalopods use their mantle cavity as a modified escape mechanism because they can forcefully expel water to jet away. they can also expel dark ink from this cavity. cephalopods have very advanced sensory organs with eyes very similar to the eyes of humans (convergent evolution)

explain the segmentation of annelids

annelids are considered segmented worms because their coelom (lined with peritoneum) is divided into a linear series of identical, fluid-filled segments running head to anus. these segments are divided by transverse membranes called septae. the organism’s digestive tract, nerve cords, and blood vessels run continuously through all segments, while excretory organs (tubular nephridia) are repeated in each segment. segments contract independently and can be regrown. the first segment of an annelid is the prostomium which contains the brain and palps (sensory organs). the second segment is the peristomium which has the mouth. the final segment is the pygidium which contains the anus. there is also a growth zone right before the pygidium

define an annelid’s setae

setae are small, stiff bristles on the outside of the worm. these are made of chitin and are equipped with tiny retractor muscles that help the worm to burrow and move

explain an annelid’s circulatory and respiratory systems

annelids have a closed circulatory system, which means the blood is enclosed entirely in vessels. however, annelids do not have lungs, and respiration occurs via diffusion through the moist surface of the body

define an annelid’s hydrostatic skeleton

annelids have a hydrostatic skeleton that is provided by their coelom. control is allowed by shifting coelomic fluid from one segment to the next

explain an annelid’s nervous system

annelids have a visible brain that consists of several cerebral ganglia, each with smaller ganglia that control each segment down the length of the nerve cords

define Polychaeta

Polychaeta (tubeworms and paddleworms) are nocturnal marine worms. each segment of these organisms have paddle-like appendages called parapodia which are covered in setae and are used for swimming, crawling, burrowing, and respiration. polychaetes can also have gills for respiration. many species burrow in the ocean floor and are filter feeders, and most have complex eyes. these organisms will also congregate in huge mating swarms driven by the phases of the moon, where they will rely on external fertilization in the water. these species also have trocophore larvae

define Oligochaeta

Oligochaeta (earthworms) are detritivores which mean they feed on dead, organic matter, making them incredibly important for aerating the soil. they use their pharynx to draw in food and the soil particles will be ground up in the crop and gizzard. they lack both parapodia and eyes, but they have a complex circulatory system with five muscular blood vessels that serve as hearts. they can reproduce asexually via transverse fission, or they are also hermaphroditic and can fertilize one another simultaneously via a clitellum. this clitellum is a small bump that is a series of segments swollen by large mucus glands. the mucus it secretes will hold the organisms together during mating. male earthworms have male pores through which the sperm emerge and two long seminal grooves will transport the sperm to the female pores on the female earthworm. a few days after sex, the fertilized eggs are released into a mucus sac that sloughs toward the end of the worm, hardens into a cocoon, and contains the eggs until they hatch

define Hirudinea

Hirudinea (leeches) suck the blood of mammals and crustaceans. they have anterior and posterior suckers for attaching to their hosts, and once attached they secrete an anticoagulant to keep the blood flowing. their coelom is greatly reduced and not divided into segments. the blood they consume is stored in special pouches within the digestive tract, so they don’t need to feed very often

explain the defining characteristics of arthropods

arthropods have an exoskeleton made of chitin that is shed during molting to allow growth. they also have paired, jointed appendages for walking, swimming, jumping, feeding reproduction, defense, sensing, and sound production. their body is segmented into regions called tagmata, which include a head, thorax, and abdomen/post-genital region. arthropods have a complete digestive system with modified mouthparts, a highly organized nervous system with complex sense organs, and complex social behaviors

define Chelicerata

Chelicerata (arachnids & horseshoe crabs) are defined by their first set of appendages: pincer-like mouthparts called chelicerae. they have no antennae and the head and thorax and fused into a single cephalothorax which bears all of the appendages. the second pair of appendages are called pedipalps which function for grasping, sperm transfer, and sense perception. chelicerata also have four pairs of walking legs

explain spiders

spiders are arachnids that use their chelicerae to immobilize prey by injecting venom and enzymes to begin digestion, allowing them to such the fluid into their pharynx

explain horseshoe crabs

horseshoe crabs are merostomata which are encased in a shell called the carapace. the carapace has compound eyes, and additional photoreceptors near the mouth. the tail of a horseshoe crab is called a telson, which also has photoreceptors. horseshoe crabs have chelicerae and five pairs of walking legs. the top portion of these legs is called the gnathobase and helps the organism to grind food before it ingests it.

define Crustacea

Crustacea (crayfish, lobsters, shrimps, crabs) all have biramous appendages, which means they branch into two. the first two pairs of appendages are antennae, and the third is a pair of mandibles. there are several other appendages that function as accessory mouthparts, aid in walking, swimming, and reproduction. crustaceans have gills for gas exchange