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SDSU Ekdale Bio101 Test 2 #2 Spring'16
Terms in this set (83)
specialized stinging cells of cnidarians
sessile (does not move) body form of some cnidarians (e.g., anemones)
mobile (something that moves) body form of some cnidarians (e.g., jellyfish)
free swimming larvum
male and female sex organs are present on the same individual (i.e., hermaphrodism)
male and female sex organs are present on separate individuals
first opening to develop in bilaterian animals; developes into mouth in proterostomes and anus in deuterostomes
an incomplete gut refers to a digestive system with a mouth but no anus
parasite that lives inside of the host organism
parasite that lives outside of the host organism
What is the difference between radial symmetry and bilateral symmetry?
In radial symmetry, body parts are arranged concentrically around an oral-aboral axis (mouth-opposite of mouth axis). In bilateral symmetry, body parts are symmetric along one axis only, which divides the body into right and left halves.
What major feature non-sponge animals from sponges (Porifera)? (I.e., what do sponges not have that all other animals do?)
True tissues. Cnidarians have diploblastic tissues (2 layers) and bilaterians have triploblastic tissues (3 layers).
List the two major clades of Cnidaria, and give an example of each.
Anthozoa (sea anemones, stony corals) and Medusazoa (jellyfish, hydras, Portuguese-man-of-war)
What is meant by alternation of generations in terms of cnidarians?
During the life cycles of many cnidarian species, an individual will live part of its life as a motile medusa (produced asexually through budding) and part of its life as a sessile polyp (produced sexually).
List the major synapomorphies of Bilateria.
Synapomorphies of Bilateria include bilateral symmetry, cephalization, and triploblastic tissues.
What is cephalization and why is it important?
Cephalization is the localization of nervous control within a distinct head region of the body. Cephalization allows motile animals to live freely (not dependant on other organisms), indicates the direction of movement, and allows development of special senses that are controlled by a brain.
What does it mean if tissues are triploblastic, and what are the names of the layers?
Triploblastic tissue consists of three tissue layers. The tissue layers, from outermost to innermost, are ectoderm (outermost tissue layer of that lines the body), mesoderm (middlemost layer), and endoderm (innermost tissue layer that lines the gut).
List the differences between Protostomia and Deuterostomia.
Protostomia is a monophyletic clade of Bilateria that is characterized by the blastopore (first opening in the embryo) developing as the mouth and position of the nerve cord along the ventral (belly) side of the body.
Deuterostomia is a monophyletic clade of Bilateria that is characterized by radial cleavage during early development, the blastopore (first opening in the embryo) developed as the anus, and position of the nerve cord along the dorsal (back) side of the body.
You are a deuterostome! (I.e., a member of Deuterostomia.) What feature(s) do you share with all other deuterostomes?
You share development of the blastopore into the anus (first opening to develop) and a dorsally positioned nerve cord.
Of the four major groups of Platyhelminthes, which are free-living and which are symbiotic parasites?
"Turbillaria" (non-monophyletic) is free-living, and Trematoda, Monogenea, and Cestoda are symbiotic parasites (trematodes and cestodes are endoparasites, monogenes are ectoparasites).
What are the three types of symbiosis, and how do they differ?
Symbiosis is the interaction of two different species in which one or both get benefits. The types of symbiosis include mutualism (both species benefit), commensalism (one benefits, but the other is unaffected), and parasitism (one benefits and the other is harmed).
Many endoparasitic species of the Platyhelminthes clade Trematoda have complex life cycles with both intermediate and definitive (final) hosts. What are the usual animals that serve as the intermediate and definitive hosts?
The usual intermediate host of endoparasitic platyhelminths (flatworms) are snails, and the definitive hosts are usually vertebrates, including humans!
the dorsal layer of skin that secretes the calcium carbonate the forms the shell in most species of mollusks
the strongest biological material known, it is the mouth part that is used for eating/feeding, it is a rasping, tongue-like organ (not found in bivalves)
helps mollusks move around, adopted for locomotion, and varies in shape among different mollusk clades. In terms of mollusks, the foot is attached to the head.
muscles that hold the valves in bivalvia together (it is the part of a scallop that we eat). It also can be used to help scallops swim actively. Predatory snails will drill through bivalvia shells to get their adductor muscle so that the valves open more freely.
setae (singular form is 'seta')
bristles, made of chitin (a hard carbohydrate), used for stabilization and movement. In marine species, the setae grow from parapodia (they are not in earthworms or leeches).
secretory organ. In lumbricidae, the clitellum secretes mucus that forms a cocoon for fertilized eggs
a hard carbohydrate. It is a tough, resistant, nitrogenous polysasccharide that is insoluble in water, alkalies, and weak acids.
the molting of cuticle and the shedding of the outer layer, when body size increases (non-cellular layer). Arthropoda shed their exoskeleten through ecdysis and female tardigrada lay their eggs in cuticle during ecdysis.
What feature(s) make a snail a protostome bilaterian animal?
Snails and other mollusks are protostome because they have ventral nerve chords. These species are also bilaterian because they have distinct left and right sides. They are also cephanized, with a distinct head regions. They also have triploblastic tissues and they are multicellular, heterotrophic species.
What feature(s) make an earthworm a protostome bilaterian animal?
Earthworms and ecdysozoan species are protostome bilaterian animals that have triploblastic tissues, equal left and right parts, they are cephilized, and their blastopore developed into a mouth first. They, like snails and mollusks, are also multicellular and heterotrophic.
List the major synapomorphies of Mollusca.
-Mantle that secretes shell the shell in most mollusca species
-Chambered heart with atria and ventricles
-Radula, which is the mouth part used for feeding
List the major synapomorphies of Annelida
List the major synapomorphy of Ecdysozoa.
Ecdysis or the molting of the cuticle
Identify the distinguishing characteristics of the following clades (i.e., how would you identify their members if you saw them in the wild?): Polyplacophora, Bivalvia, Gastropoda, Cephalopoda, "polychaetes", Lumbricidae, Hirudinidae, Nematoda, Onycophora, Tardigrada
-Polyplacophora - chitons, multi-valved
-Bivalvia - clams, has two valves
-Gastropoda - snails, single valved, or slugs, having no shell
-Cephalopoda - squids and octopuses, single valved
polychaetes - marine annelids, setae grow from parapodia
-Lumbricidae - freshwater and terrestrial species, have setae but no parapodia, earthworms
-Hirudinidae - most are terrestrial, absent setae
-Nematoda - free-living, mutualistic, and parasitic species, non-chitinous exoskeleton composed of collagen, no legs
-Onycophora - only terrestrial, chitin in exoskeleton, unjointed appendages with claws, velvet worms.
-Tarigrade - microscopic, living in water droplets on moss and lichen, chitinous exoskeletons that are shed, unjointed legs with claws
Which major clade of mollusk is the most diverse in terms of the greatest number of species?
Gastropoda (~70,000 species) - these are the snails, slugs, limpets, and abalones
There is only one clade of mollusk that includes fully terrestrial (land dwelling) species. Which clade is it?
Gastropoda - most are marine, but some are freshwater and some are fully terrestrial.
Bivalve molluks have lost their radula. How do they eat?
They eat by using their incurrent and excurrent siphons to move water over their gills, which filter their food, food is then trapped in mucus that is transported to their mouth via cilia.
Do "worms" (Platyhelminthes, Annelida, Nematoda, and Onycophora) form a monophyletic group? Why or why not?
No, because Platyhelminthes and Annelids are more closely related to mollusks than they are to Nematodes. The Nematoda are more closely related to Arthropods.
Annelids have metameric segmentation. What does that mean?
Metameric segmentation is when the Annelid is segmented, the body is divided into serial parts divided by septa. These parts are the same.
Briefly discuss the lifestyle(s) of nematodes. Are they free-living, symbiotic, or parasitic?
Nematodes can be free-living, multualistic, or parasitic. Free-living nematodes are those like the C. elegans, a "model organism" we used for scientific research. It was the first multicellular organism to have its genome sequenced. Mutualistic nematodes live in the intestines of iguanas and help the iguanas digest plant material. Parasitic nematodes can live in our intestines, sucking our blood and penetrating our lungs.
What feature does members of Onycophora share with members of Tardigrada, but not with Nematoda?
Onycophora and Tardigrade both have unjointed legs/appendages with claws and chitinous exoskeletons. Nematoda do not have legs/appendages or claws. They also do not posess chitinous exoskeletons. Instead, Nematodes have exoskeletons composed of collagen.
What is cryptobiosis, and how has it led to the success of tardigrades?
Cryptobiosis is the state of suspended animation, in which tardigrades shrivel up, drying up their bodies and stopping their metabolism. This allows tardigrades to survive for over 10 years after they run out of water or if they are placed in extremely low temperatures or in space. Think of Ant Man!
pincer-like first pair of legs in crustaceans, used for seizing and crushing
pair of head appendages on members of Chelicerata (including arachnids)
second pair of appendages in arachnids
shell-like plate (calcified chitin) covering the cepahlothorax of some crustaceans
compound body segments of arthropods formed through the fusion of two or more segments (e.g., head, thorax, abdomen)
respiratory openings along the sides of abdominal segments
What feature(s) make arthropods ecdysozoan protostome bilaterian animals?
Arthropods are ecdysozoans in that they have an outer, non-cellular cuticle layer that is shed (except in Nematoda). Arthropods are protostomes in that the blastopore (first opening) develops into the mouth, the nerve cord is ventral, and the developing embryo divides with spiral cleavage. Arthropods are bilaterians in that they are bilaterally symmetrical, have triploblastic tissues, and are cephalized (nervous structures concentrate in a head region). Arthropods are animals in that they are multicellular heterotrophs that gain nutrition through ingestion.
List the synapomorphies for Arthropoda, Chelicerata, Myriapoda, Crustacea, and Hexapoda.
-chitinous exoskeleton (shed); jointed (articulated) appendages; compound eyes; segmented bodies
- two tagmata (cephalothorax and abdomen); chelicerae (first pair of appendages developed as "fangs")
-one pair of antennae; loss of compound eyes; two tagmata (head and trunk)
-compound eyes on stalks; two pairs of antennae; biramous appendages; two tagmata (cephalothorax and abdomen)
-three pairs of uniramous legs; abdominal legs lost; three tagmata (head, thorax, and abdomen); two pairs of wings
How do the tagmata differ among different arthropod groups?
Tagmata are the segmented, functional body parts of arthropods. Myriapods, chelicerates, and crustaceans have two tagmata (head and trunk in myriapods; cephalothorax and abdomen in crustaceans and chelicerates). Hexapods have three tagmata (head, thorax, and abdomen).
What does it mean for an arthropod to be "biramous" or "uniramous", and which arthropod groups are characterized by each term?
"Biramous" refers to appendages that have two branches, whereas "uniramous" appendages have only a single branch (unbranched). Crustaceans are biramous, and all others are uniramous.
Distinguish between different myriapod clades.
Chilopods (centipedes) have one pair of legs per trunk segment, whereas diplopods (millipedes) have two legs per trunk segment.
How do myriapods differ from other arthropod clades?
Myriapods have two tagmata (head and trunk) and they lack compound eyes (secondarily lost).
How might you tell the difference between a chilopod centipede and a polychaete annelid?
Chilopod arthropods (centipedes) and polychaete annelids look superficially similar because they both have elongate, segmented bodies. However, chilopods have a chitinous exoskeleton (absent in annelids) and jointed appendages (polychaetes have parapodia with setae that look like appendages).
What is the advantage of ecdysis (molting) in arthropods such as crustaceans?
Molting is initiated hormonally when inhibiting hormones are decreased and molting hormones are increased. During the pre-molt phase, the old cuticle thins and separates from the epidermis. Ecdysis itself occurs when the cuticle ruptures and the animal "backs out" of its old exoskeleton. In the post-molt phase, the new cuticle stretches and thickens.
What is the most diverse clade of Haxapoda called?
The most diverse clade of hexapods (insects) is Coleoptera (beetles).
Distinguish between complete and incomplete metamorphosis in hexapods.
Incomplete metamorphosis is a gradual transition from larvae to adults with an intermediate nymph stage. In complete metamorphosis, the larva develops dramatically within a chrysalis (pupa) before emerging as an adult. (No nymph stage in complete metamorphosis.)
Distinguish between the wings of Lepidoptera, Coleoptera, Hymenoptera, and Diptera in terms of number and form. (These are four of several major clades of hexapods.)
- butterflies and moths with two pairs of large, scale-covered wings
- beetles with two pairs of wings, forewings covered by protective shell (elytra)
- ants and bees with two pairs of membranous wings
- true flies with one pair of wings (hindwings modified as halteres)
Would you consider crustaceans to be predatory, suspension feeders, parasites, or any combination of those?
Crustaceans can predatory (e.g., malacostracans such as crabs), suspension feeders (e.g., maxillopods such as barnacles), or even parasitic (e.g., maxillopods such as fish lice)
How does the cuticle differ between crustaceans and all other arthropods?
The cuticle of all arthropods is composed of chitin. However, the cuticle in crustaceans is calcified to form a carapace.
What is an evolutionary adaptation shared by Trematoda, Monogenea, and Cestoda?
Many cnidarians, such as jellyfish, develop from larva to adult through an "alteration of generations". During an early stage of jellyfish development in particular, the animals attach themselves to the undersides of rocks. Later on, they become free swimming adults. What is the body form that the animals assume while they are attached to rocks? (Hint: this is the body form of adult sea anemones.)
One of the largest invertebrates on our planet, the colossal squid Mesonychoteuthis hamiltoni, reaches maximum lengths of 40-50 feet and can weigh over 1,500 lbs! Although sightings of living colossal squids are rare, pieces of the horn-like beak have been discovered in the gut contents of sperm whales. In life, the beaks surround a tongue-like organ with a raspy, scraping surface similar in structure to other smaller mollusks. To what major mollusk clade does Mesonychoteuthis belong?
The formation of the head in the most recent common ancestor of Bilateria is known as:
Which of the following is responsible for secreting the shell found in the Mollusks?
In protostomes, the nervous system is located:
Suspension-feeding mollusks with two valves include _____________.
Bivalvia (clams, mussels, scallops, and oysters)
Mutualism, commensalism, and parasitism are types of:
What type of symmetry do cnidarians (anemones and jellyfish) have?
Jellyfish, the Portuguese-man-of-war, and freshwater hydras belong to the major Cnidarian clade named:
Animals that shed their outer, non-cellular layer belong to which of the following clades?
When two earthworms (Lumbricidae) love each other very much, they come together to make baby earthworms. During the process of baby making, mucus is secreted by a collar or saddle-shaped structure known as the _________ to surround the fertilized eggs.
Cryptobiosis, a form of biological stasis that is exhibited by members of Tardigrada, occurs in response to?
adverse climatic conditions
Which of the following characters is a synapomorphy for the phylum Annelida?
the presence of metameric segmentation
Which one of the following does NOT represent an arthropod lineage?
While making your bed one morning, you encounter the shed cuticle (composed of the polysaccharide chitin) that was left by a small animal that had been crawling through your bed sheets. The body is approximately half an inch long, and it appears to be divided into two functional body segments. One of the segments possesses a number of paired, jointed appendages, and the other segment is legless. It appears that the animal shed the cuticle several days ago, and I'm sure it's no longer in your bed... What kind of animal shed its cuticle in your sheets?
A chelicerate (Arthropoda)
The telson is a tail-like structure in the Merostomata (horse-shoe "crabs"), and it develops a venomous stinger in some Arachnida (scorpions). Two what major arthropod clade do horse-shoe crabs and scorpions belong?
Compound eyes, a chitinous exoskeleton, and jointed appendages are synapomorphies for the ?
What are chelicerae?
modified mouth parts
Wow, you must really love rutabagas! While working in your garden, planting rutabaga seeds, you uncover a small animal in the soil. The animal is bilaterally symmetrical, but it lacks any sort of appendage for locomotion. Under the microscope, you notice that the animal has an unsegmented and non-cellular cuticle composed of collagen (which the animal eventually would shed) and longitudinal muscles, but no evidence of circular muscles. What type of animal was burrowing through your precious rutabaga garden?
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