LAB 5 ANIMAL DIVERSITY IV: PHYLUM ARTHROPODA.

INTRODUCTION

De Phylum Ardropoda be de largest and most diverse uh all animal phyla (Fig 5.1). Mo'e dan dree quarters of de animals on eard is ardropods, and most uh dese is insects. Mo'e dan 900,000 species gots been described, and if biologists gots de oppo'tunity to 'esplo'e da damn rain fo'ests befo'e dey is completely burned t'de ground, a likes numba' gots'ta probably be discovered.

 Ardropods gots deir skeletons on de outside uh deir bodies, rada' dan on de inside (dey gots an exoskeleton; while our internal skeleton be called an endoskeleton.) De phylum's dojigger be based on dis feature (Ardropoda means "joint-foot" referrin' t'de 'esternal joints in de skeleton dat allow movement). Dere is bod advantages and disadvantages t'bein' inside out (aldough de majo'ity opinion be clearly dat it's our skeletons dat are oddly situated). De advantages seem t'outweigh any disadvantages, judgin' fum de phylum's success and diversity (ardropods include in deir ranks crabs, lobsters, spiders, mites, and da damn vast numba' of different insects).

 Mo'e dan nuthin, de 'esoskeleton gots allowed da damn ardropods t'diversify and move into niches dat wuz previously inaccessible. Dey wuz de fust beasts t'successfully colonize land (de 'esoskeleton preadapted dem fo' terrestrial habitats since it provided bod suppo't and protecshun fum dryin' out). Insects flew long befo'e nuthin likes some bird 'esisted. Some gots'ta have been quite impressive; relatives uh today's dragonflies wid win'spans uh nearly a meter flew de Triassic skies (ova' 230 million years ago and pre-datin' de fust birds by nearly 100 million years). We even owe da damn presence uh flowers t'insects (most flowers is constructed t'attract insects fo' pollinashun). In dis labo'ato'y we gots'ta only touch on de diversity in de Phylum Ardropoda. WORD!

Figure 5.1. Numerical Distribushun uh Named Animal Taxa. WORD!

 

EXERCISE 5.1 Primitive Ardropods- De Extinct Trilobita. WORD!

 

MATERIALS NEEDED:

§         Fossilized trilobites and plasta' casts.

 

            Trilobites is de most primitive uh de ardropods. Aldough dey are now 'estinct, deir hard 'esoskeletons are so's well-preserved and plentiful in de fossil reco'd dat much be knode about deir anatomy, diet, embryology, and even behavio' (about 4000 species are described). Examinashun uh deir appendages and general body structure show dat most wuz marine bottom-dwellin' o'ganisms. De structure uh deir moudparts and X-rays uh deir digestive systems indicate dat deir diets included seaweeds, coelenterates, and mollusks. Some wuz probably scavengers, feedin' on o'ganic debris in de muck much as some annelids do today. Slap mah fro! Trilobites reached deir height of distribushun and abunboogie durin' de Cambrian and Ordovian puh'iods (about 500 million years ago).

PROCEDURE:

1. Subphylum Trilobita. WORD! Examine da damn fossilized remains and museum casts uh trilobites. De body be divided into dree main secshuns, dig dis: an anterio' shield-shaped cephalon (haid), some segmented body (de do'ax), and some plate-likes pygidium at da damn rear. Ah be baaad... De body be longitudinally divided into dree regions by some deep furrow (dese dree segments, each divided into dree po'shuns be de o'igin uh deir dojigger). De cephalon had some pair uh antennae (probably not preserved in yo' specimen). De presence uh a raple antennal pair be one reason dey is often placed widin de Subphylum Mandibulata. A pair uh compound eyes kin be identified on most fossils (aldough some wuz blind). De eyes kin be so's well preserved dat microscopic 'esaminashun of deir lens systems be possible. De appendages on de ventral surface uh de animal included walkin' legs, filaments, spines, and gills. Dese ventral structures is not usually so's well preserved. Sketch some well-preserved specimen and label de visible structures.

 

EXERCISE 5.2 Subphylum Chelicerata- Class Merostomata and Arachnida. WORD!

MATERIALS NEEDED:

§         Preserved and Livin' Organisms, dig dis: class Merostomata, dig dis: ho'se kicker crabs (Limulus polyphemus); class Arachnida, dig dis: sco'pions, various spiders, ticks, and mites.

 

            Members uh de Subphylum Chelicerata gots no antennae and feedin' appendages called chelicerae. Deir body be divided into two main secshuns, dig dis: an anterio' cephalodo'ax and some posterio' abdomen.

PROCEDURE:

1. Class Merostomata. WORD! Dis class be represented by only foe species uh animals commonly knode as "ho'se kicker crabs". Ho'se kicker crabs is common inhabitants uh de coastal marine boozes off de No'd American Atlantic coast and along de Gulf uh Mexico. 'S coo', bro. Dey spend most uh deir time burrowin' drough soft mud lookin' fo' wo'ms, mollusks, and oda' tasty tidbits. Examine a livin' o' preserved specimen uh de ho'se kicker crab, Limulus polyphemus. De anterio' cephalodo'ax be covered wid a ho'se kicker-shaped carapace, fum which de animals derive deir common dojigger. Two large compound eyes and some pair uh small simple eyes (at da damn anterio' end uh de median ridge) is on de do'sal carapace. De abdomen (posterio' t'de carapace) bears rows uh sho't spines and some sin'le large telson. 'S coo', bro. Despite its fo'midable appearance, de telson be used neida' fo' offense no' defense, and livin' animals kin be safely handled. When annoyed, ho'se kicker crabs fold deir abdomen unda' de carapace t'protect da damn mo'e delicate ventral appendages. Turn yo' animal upside to 'espose da damn ventral surface. De smallest uh de pincers is de chelicerae, feedin' appendages dat is characteristic uh dis subphylum. WORD! De moud be located directly behind dem. WORD! Dere is five pair of walkin' legs. Scribblin' gills (de page-likes appendages on de abdomen) is used fo' respirashun and swimmin'. De anus be plum anterio' t'de telson. 'S coo', bro.

2. Class Arachnida. WORD! De arachnids is de most successful group in dis subphylum. WORD! Dey include spiders, sco'pions, mites, and ticks and wuz among de fust animals t'move onto land. Aldough dis group be probably de most unpopular uh all invertebrates, dey is ecologically impo'tant (spiders, fo' 'esample, devour mo'e insect pests dan do birds).

 

§         Sco'pions, dig dis: Sco'pions is most easily recognized by de stin'in' barb at da damn tip uh deir abdomen. Gently remove some preserved sco'pion fum its vial. De body be divided into an anterio' prosoma and da damn posterio' abdomen. As in de ho'se kicker crabs, de prosoma be covered wid some do'sal shield (de carapace). Two pincher-likes appendages (de pedipalps) is used t'manipulate prey (mostly insects and spiders). Dere is foe pair uh walkin' legs. Examine da damn oda' sco'pions on display. Slap mah fro!

 

§         Spiders, dig dis: Posishun a garden spida' (o' similar beast) unda' a dissectin' microscope. De body is divided into an anterio' cephalodo'ax and some posterio' abdomen. From a do'sal view, eight eyes is clustered at da damn front uh de cephalodo'ax (de eyes is de shiny brother dots). On de ventral side note da damn fangs at da damn base uh de movable chelicerae. Nearby ya' gots'ta find two small leg-likes appendages (de pedipalps). Examine da damn pedipalps unda' de highest available magnificashun. If yo' animal be an adult o' penultimate ("teenage") male, de last segment uh de pedipalps be 'spanded into some copulato'y o'gan. 'S coo', bro. De pedipalps is followed by foe pair uh walkin' legs. De last segment of each leg be called da damn tarsus (it serves as some foot). Trace yo' way back toward da damn body and identify de metatarsus, tibia, patella, femur, and a small coxa at da damn base uh de leg. What it is, Mama! De sternum be de flat shield between de eight coxae on de ventral surface. Identify de entrance t'de scribblin' lungs (two slits on de anterio' part uh de abdomen) and da damn spinnerets (fin'er-likes appendages at da damn posterio' tip uh de abdomen). Silk glands in de abdomen is connected t'de spinnerets. Examine da damn oder spiders on display. Slap mah fro!

 

§         Mites and ticks. De abdomen uh mites and ticks gots lost any 'esternal evidence uh segmentashun and be fused t'de prosoma. De carapace derefo'e 'estends upside de entire body. Slap mah fro! Mites is a group uh small (<1 mm), mostly parasitic arachnids (aldough free-livin' mites kin inhabit bod terrestrial and aquatic ecosystems). Ticks, on de oda' hand, is usually larga' and is obligate 'esternal blood-suckin' parasites droughout deir entire lives.

 

EXERCISE 5.3 Subphylum Crustacea. WORD!

MATERIALS NEEDED:

§         Preserved Organisms, dig dis: preserved crayfish fo' 'esaminashun, various crustaceans on display. Slap mah fro!

§         Livin' Organisms, dig dis: culture vial uh de booze flea, Daphnia. Live crayfish and/o' oda' crustaceans.

§         Miscellaneous, dig dis: microscopes, slides, slide covers, eyedroppuh's, dissectin' kits,

 

            Members uh de subphylum Crustacea gots two pair uh antennae and feedin' appendages called mandibles.

 

PROCEDURE:

1. Crustacean Diversity. Slap mah fro! Crustaceans is an 'estremely diverse group uh primarily aquatic ardropods wid two pair uh antennae. De class includes such culinary delights such as shrimp, lobsters, crayfish, and barnacles (barnacles?). Aldough most is free-livin', some few is parasitic. Co' got d' beat! Primitive crustaceans gots dree main body parts, dig dis: some haid, some do'ax, and an abdomen. 'S coo', bro. Dere be a tendency, however, fo' de haid and do'ax t'fuse and fo'm some sin'le cephalodo'ax. Slap mah fro! Examine da damn preserved crustaceans on display. Slap mah fro! Note da damn variability in deir body structure and different feedin' adaptashuns. If available, snatch some few minutes t'observe da damn general behavio' uh livin' animals.

2 Examinashun uh a Livin' Crustacean, dig dis: Daphnia. Daphnia is commonly knode as "booze fleas" cuz' of de apparent similarity in deir locomoshun t'dat uh de terrestrial insect. Man! Dey is common inhabitants uh freshbooze ponds and is an impo'tant component uh dese food chains. Remove some Daphnia fum de culture vial

Figure 5.2. Majo' o'gans and appendages uh de booze flea, Daphnia.

 

    and make some wet mount. Man! De body be covered in some clam-shell-likes carapace (jimmey on de ventral surface). A raple compound eye kin be seen movin' in de haid (Fig 5.2). De antennules is small and located at da damn tip uh de rostrum ("nose"). Also note da damn prominent second antennae (rapid flicks of which is used fo' swimmin'). Observe da damn movements uh de trunk appendages bediggin' hoth de carapace. Filterin' setae on dese appendages sift microscopic o'ganisms fum de booze. Food be passed fo'ward t'de moud t'be digested (owin' t'deir transparent nature, food kin usually be seen widin de digestive tract). Males is rare and is seen only at certain times uh de year, so's yo' specimen be likesly t'be dudette. If ya' is lucky ya' may see developin' embryos widin de brood chamber. Ah be baaad... Use protoslo t'retard de movement uh yo' specimen o' switch t'a prepared slide. Sketch yo' specimen in de results secshun and identify as many uh de structures as possible.

3. Crayfish External Anatomy. Slap mah fro!  Obtain a preserved crayfish and identify each uh de appendages and structures indicated in Figure 5.3 and 5.4. Each uh de appendages be based on de same embryonic structures and, unlikes de booze flea, show great structural diversity (Figure 5.5). Examine each uh de appendages and speculate as to deir specializashuns. Reco'd yo' observashuns in de results secshun. De carapace be a continuos chitinous structure dat covers de joined haid and do'ax uh de crayfish. Lop some boogie. Evidence uh de suturin' kin be seen at da damn cervical groove. De main senso'y structures is de eyes, antennae, and antennules. Note also de various fros and pits coverin' de surface uh de body dat serve mechano'eceptive and chemo'eceptive funcshuns. If yo' animal be a male, de fust pair uh swimmerets gots'ta be 'espanded into copulato'y o'gans while de anterio' swimmerets uh dudettes is similar t'de feadery posterio' swimmerets. Move one uh de walkin' leg appendages and not deir range of movement. Man! De “extra” limb segments (compared t'our limbs) are adaptashuns t'allow graceful movement since ball-and-socket joints (such as yo' shoulder) is not possible wid an 'esternal skeleton. 'S coo', bro. Make some sketch showin' de range uh move uh each uh de leg secshuns in de results secshun.

4. Crayfish Internal Anatomy. Slap mah fro! Begin yo' dissecshun by cuttin' along de suture lines (cervical groove; Figure 5.3) between de haid and do'ax uh yo' specimen (use scisso's). Next, gently lift da damn carapace fum de underlyin' tissue as a left- and right-hand flap. Jes hang loose, brud. Note da damn structure uh de underlyin' gills. Gently tease da damn gills apart t'note deir associashun wid de walkin' legs (see also Fig 5.5). Use yo' shears t'remove da damn din chitin coverin' t''spose de underlyin' o'gans. Note, dig dis: You's gots'ta be enterin' de animal fum de do'sal not fum some lateral view as shown in figure 5.6. Locate da damn heart (it may still be attached t'de carapace if yo' wuz not gentle durin' yo' initial dissecshun. If de heart be in place, yo' should also be able t'locate da damn puh'icardial sinus and da damn do'sal arteries shown in figure 5.6. Remove da damn heart and de remainda' of de puh'icardial sinus t'fully 'espose da damn digestive glands (much larga' dan shown in de figure) and two-part stomach consistin' uh a cardiac and pylo'ic secshun. If yo' animal be a dudette and be in breedin' condishun, ya' may also find some black mass (de ovaries). Spread da damn digestive glands t''spose da damn intestines and trace deir o'igin at da damn pylo'ic stomach. Lop some boogie. Remove da damn digestive glands, intestine and stomach fum de do'acic cavity (snip de cardiac stomach so dat da damn esophagus remains attached t'yo' animal). Note da damn structure uh de nervous system in yo' animal. Locate da damn segmental ganglia and paired ventral nerve co'ds. Follow de nerve co'd in an anterio' direcshun t'locate da damn circumpharyngeal connective. Follow it furda' to identify de star-shaped brain plastered on de interio' uh de haid between de eyes. Note da damn various nerves runnin' fum de brain t'de various senso'y structures uh de haid. Locate da damn green gland, which serves as some kidney in de crayfish. Lop some boogie. If ya' gots difficulty, fust find da damn renal po'e (Fig 5.4), and da damn green gland gots'ta be located directly behind it. Man! Note also de paired muscles attached near t'de green gland. Whut be de funcshun uh dese muscles? Continue yo' dissecshun by openin' de abdomen. 'S coo', bro. Why is de abdominal 'estenso' and flexo' muscles uh differin' size?        

 

Figure 5.3. Crayfish 'esternal anatomy. Slap mah fro!

Figure 5.4. Crayfish moud parts and associated structures.

 

Figure 5.5. Biramous Appendages uh a Crustacean. 'S coo', bro.

 

 

Figure 5.6. Internal Anatomy uh a Crayfish. Lop some boogie.

 

 

EXERCISE 5.4 Subphylum Uniramia. WORD!

MATERIALS NEEDED:

§         Preserved Organisms, dig dis: insects, dig dis: preserved insects fo' display, grasshoppuh's, supuh'class Mah'riapoda, dig dis: preserved centipeds and millipeds fo' demonstrashun.

§         Prepared Slides, dig dis: insects, dig dis: prepared slides uh chewin', piercin'/suckin', siphonin', and spongin' moudparts (display o' available t'each student), prepared slides uh antenna types and slide uh honeybee legs (o' preserved wo'ka' bees), demonstrashun slide(s) uh insect tracheal systems.

§         Miscellaneous, dig dis: compound microscopes, slides, slide covers, eyedroppuh's.

 Members uh de subphylum Uniramia gots one pair uh antennae and feedin' appendages called mandibles.

1. Supuh'class Hexapoda, dig dis: De Insects. As previously menshuned, insects is de most successful uh all animal phyla. WORD! Dey diffa' from crustaceans by havin' a raple pair uh antennae (rada' dan two) and legs based on some uniramus plan (wid unbranched appendages). De 'esoskeleton, dough similar in structure to dat uh crustaceans, lacks significant calcium deposits. Characteristics dat separate dem fum de oda' ardropods include dree pairs uh legs and (usually) two pairs uh win's. Examine da damn preserved and livin' insects on display to appreciate da damn variability in deir body plans and adaptashuns.

 

§         External Anatomy of Representative Insects (Wid Particular Attenshun t'de Grasshoppuh'). Obtain some preserved grasshoppuh' and locate da damn followin' structures. De body is divided into dree segments, some haid, do'ax, and abdomen. 'S coo', bro.

               De Haid. Examine da damn haid unda' a dissectin' microscope payin' particular attenshun t'de moudparts, de dree simple eyes (between de antennae) and da damn compound eyes. De grasshoppuh''s moudparts is adapted fo' chewin'. Compare da damn structure uh chewin' moudparts t'dat of piercin'/suckin', siphonin', and spongin' moudparts on display. Slap mah fro! De antennae is senso'y structures wid bod mechano'eceptive (sense uh touch) and chemo'eceptive (sense uh taste/smell) funcshuns. Compare deir structure wid dat uh oda' antennae on display. Slap mah fro!

               De Do'ax. Slap mah fro! Return yo' attenshun t'de grasshoppuh'. A close 'esaminashun uh de do'ax gots'ta show dat it's real made down uh dree fused segments, each wid some pair uh legs. De most anterio' segment be de prodo'ax (followed by de mesodo'ax and metado'ax. Slap mah fro! Aldough most senso'y structures is on de animal's haid, de ear (tympanum) be located above da damn dird leg of some grasshoppuh'. Two pair uh win's is attached on de do'sal surface uh de do'ax. Slap mah fro! Whut differences kin be seen in de structure uh de fo'ewin' and hind win'?. Which do ya' dink be most impo'tant fo' flyin' (and why?; results secshun). Examine some leg unda' a hand lens o' dissectin' microscope. De basal segment uh an insect's leg be called da damn coxa. WORD! Dis be followed by some sho't trochanta' and da damn fust long segment uh de leg (femur). De tibia (second long segment) be attached t'de femur. Ah be baaad... Several sho't segments (a metatarsus and da damn tarsi) follow de tibia and serve as some "foot". De legs of insects is excellent 'esamples uh de adaptashun in fo'm t'funcshun.

               De Abdomen. 'S coo', bro. De segmentashun uh de abdomen be clearly visible. Locate da damn spiracles on each segment. Man! Dese po'es serve as de entrances t'de insect's tracheal system (used fo' respirashun). If available, review de demonstrashun slides of insect tracheae. De posterio' po'shuns uh de abdomen is modified as copulato'y and egg-layin' structures.

 

2. Supuh'class Mah'riapoda. WORD! Mah'riapods include da damn centipedes and millipedes (de term "Mah'riapoda" means "many footed"). Like da damn insects, dey is primarily terrestrial in habits, gots some sin'le pair uh antennae, uniramus appendages, and moudparts based on mandibles. Unlikes de insects, de mah'riapod body be divided into only two segments, some haid and trunk (instead of an insect's dree segments- de haid, do'ax, and abdomen) and da damn eyes are not as complex. Slap mah fro! De trunk segments may range fum some few t'mo'e dan a hundred.

 

§         Class Chilopoda- de Centipedes. Centipedes gots one pair uh legs puh' body segment and poison glands (most, however, is not dangerous t'humans). Dey prefa' moist places and feed on eardwo'ms and insects. Examine da damn centipedes on demonstrashun so dat ya' kin recognize deir general structure.

§         Class Diplopoda- de Millipedes. Millipedes gots two pairs uh legs puh' body segment and do not possess poison glands. Like centipedes, dey prefa' moist habitats, but dey is eida' herbivo'ous o' scavengers.