Biology Lab 12 Biology lab, Lab Reports of Chemistry

Download Biology Lab 12 Biology lab and more Lab Reports Chemistry in PDF only on Docsity! synapomorphies include a complete digestive system (runs from mouth to anus), a double ventral nerve chord, and excretory organs called the Maphighian tubes. Sexes are separate: arthropods copulate and have internal fertilization. Most arthropods care for the eggs in some way, either by laying eggs with protective shells in or on a food source or by carrying them around on their bodies until the eggs hatch. Females carrying eggs are called gravid females. Larvae are often very different from adults and undergo metamorphosis in a short period of time. ACTIVITY 1: Arthropod Dissection In this laboratory, you will be working in groups of two on the dissection of the organism assigned to you by the professor. You will be responsible for identifying the external and internal features of your organism using the Photographic Atlas and other resources as provided by your instructor. (NOTE: Don't forget to check out the other specimens that are available at the rear of the lab.) Exercise 1: Anatomy of Crayfisb As a member of the Class Crustacea, the crayfish shares synapomorphies with other crustaceans. This includes jointed, paired, and biramous appendages, two pairs of antennae, and three body regions (the head, thorax, and abdomen). Crayfish are known to be scavengers, but they also prey ion other invertebrates. The mouth is surrounded by appendages modified for feeding, and there is a well-developed digestive tract. Dorsal, anterior, and posterior arteries carry hemolymph (blood plus lymph) to tissue spaces (hemocoel) and sinuses. In contrast to vertebrates, there is a ventral solid nerve cord. Crayfish are adapted to an aquatic existence. External Anatomy 148 1. Obtain a preserved crayfish, and place it in a dissecting pan. You will draw the exterior and interior of the crayfish in the boxes following the dissection instructions. Make sure to label the balded structures on your drawings as you go though the dissection. 2. Identify the chitinous exoskeleton. 3. Arthropods are distinguished by metameres (repeating body segments) that fuse to form different body regions (tagmata; tagma sigular). There are two tagmata in the crayfish. The first is the cephalothorax (fusion of the head and the thorax), which is covered by a carapace. The second is the abdomen, which consists of several metameres that go all the way down to the tail. Q: Is each region specialized for its function? -~-+re..:~5 ___________ _ Q: Which body region of the crayfish is most obviously segmented? BrvleN\e ~ 4. Find the antennae, which project from the head. Crustaceans also contain a secondary set of smaller antennae (antennule). At the base of each antenna, locate a small, raised nipple containing an opening for the green glands, the organs of excretion. Crayfish excrete a liquid nitrogenous waste. Q: The nitrogenous waste would result from the breakdown of which group of macromolecules? pro\.t-...:.n:S ~ /'\LAc.l£c..i, <:U:c.l5 5. Locate the compound eyes, which are composed of many individual units (ommatidia) for sight. Identify the rostrum, the projection of the carapace above the eyes. 6. Identify the six pairs of feeding appendages around the mouth for handling food. 7. Find the five pairs of appendages attached to the cephalothorax. The most anterior pair is the pincer-like claws (chelipeds). The other four pairs are walking legs. Q: How many appendages are chelate (that is, pincer-like with opposing claws)? ·3 8. Locate the five pairs of swimmerets on the abdomen. In the male, the anterior two pairs are stiffened and folded forward. They are copulatory swimmerets and aid in the transfer of sperm during mating. Q: Are the anterior swimmerets different from the posterior pair? U. (:!: 5 - v~-=- ---- 9. In the female, identify the seminal receptacles , a swelling located between the bases of the third and fourth pairs of walking legs. Sperm from the male are deposited in the seminal receptacles. In the male, identify the opening of the sperm duct located at the base of the fifth walking leg. In addition, on either side of the middle walking legs are two openings, which lead to the oviduct. The eggs are released onto the exterior region between the walking legs, allowing for external fertilization.68 Q: What sex is your specimen? _t.::....e=--..c~- -:..._ ______________ _ (Make sure to view a crayfish of the opposite sex and note the differences). Q: How can you differentiate a male crayfish from a female crayfish? ~)(.\m- ~\MM-u- (<U-S ~ o.Q. tairt O('d. f~~= Q: How would you differentiate walking legs from swimmerets? WO-\\.~~ ~~ 0-("J! a~4-5-es ~ dt-d\; :tc 10. Find the last abdominal segment, which bears a pair of broad, fan-shaped uropods, which, together with a terminal extension of the body (the telson), form a tail. Q: ~oyt does the structure of the uropods correlate to its function? rw (M))0Jd:S (.,.X,c\( [c,'el¼,, - lVI~ :!k h.l'=>ol'c ~"- oede.r 68 Mac0rganisms2: Crayfish Anatomy; https://www.youtube.com/watch?v=2cBGuEDxvNo 149 Exercise 2: Anatomy of Grasshopper The grasshopper is an insect. The presence of a single pair of antennae and uniramous appendages among other features identifies insects as belonging to the Class Hexapoda. Like the crustaceans, the body of insects is separated into the head, thorax, and the abdomen, but there are no appendages attached to the abdomen. Insects are adapted to life on land. In insects with wings, such as the grasshopper, wings are attached to the thorax. Respiration is by a highly branched internal system of tubes, called tracheae. External Anatomy 152 1. Obtain a preserved grasshopper, and study its external anatomy. With the help of the Photographic Atlas, you will draw the exterior and interior of the grasshopper in the boxes following the dissection instructions. Make sure to label the bolded structures on your drawings as you go though the dissection. 2. 3. 4. 5. 6. 7. Identify the three tagmata: head, thorax, and abdomen. The grasshopper's thorax consists of three fused segments: the large anterior prothorax, the middle rnesothorax, and the hind rnetathorax. Identify the first pair of legs attached to the prothorax. Then find the second pair of legs and the outer pair of straight, leathery forewings attached to the mesothorax. Finally, locate the third pair of legs and the inner, membranous hind wings attached to the metathorax. Each leg consists of five segments. The hind leg is well developed and used for jumping. Q: How How many pairs of legs are there? C. ~(}\~ed. le5s Q: Is locomotion in the grasshopper adapted to land? Explain. L('{~ , -Hi-e. Vl~S$ 1 ~£ ~~ Sc1oord.: ~ fu: 1JJo.l lL~~~ ~ Spread the wings. Note that they do not have the same shape and consistency (texture). This because the forewing and hindwing are specialized for different purposes. The hindwings are used for flight while the forewings are used for balance and stabilization. Use a hand lens or dissecting microscope to examine the grasshopper's special sense organs of the head. Identify the antennae (a pair of long, jointed feelers), the compound eyes, and the dot-like simple eyes ( ocelli). Remove the mouthparts {palp) by grasping them with forceps and pulling them out. Arrange them in order on an index card, and compare them to the diagram of the head and mouth parts in the Photographic Atlas. These mouthparts are used for chewing and are quite different from those of a piercing and sucking insect. Identify the tympana (singular, tympanum), one on each side of the first abdominal segment. The grasshopper detects sound vibrations with these membranes. .v ~~ ~ ~ ~ ~ ~ ~ ~ t>¢ ~ v ¢ ~ 8. 9. L~cate the spiracles, along the sides of the abdominal segments. These openings allow air to enter the tracheae, which constitute the respiratory system. Find the ovipositors, four curved and pointed processes projecting from the hind end of the female. These are used to dig a hole in which eggs are laid. The male has claspers that are used during copulation. Q: How What sex is your grasshopper? r~e.. _._-'-'-J...::........,~"""-- --------- L ab e I the external structures of the grasshopper. Internal Anatomy 1. Remember to draw and label (bolded terms) of the internal grasshopper as you proceed through the dissection. 2. Detach the wings and legs of the grasshopper. Turn the organism on its side, and use scissors to carefully cut through the exoskeleton (dorsal to the spiracles) along the full length (from the head to the posterior end) of the animal. Repeat this procedure on the other side. 3. Cut crosswise behind the head so that you can remove a strip of the exoskeleton. If necessary, reach in with a probe to loosen the muscle attachments and membranes. 4. Pin the insect to the dissecting pan, dorsal side up. Cover the specimen with water to keep the tissues moist. 153 154 5. Identify the heart and aorta just beneath the portion of exoskeleton you removed. A grasshopper has an open circulatory system. Remove the heart and adjacent tissues. 6. Locate the fat body, a yellowish fatty tissue that covers the internal organs. Carefully remove it. 7. Find the tracheae, the respiratory system of insects. Using the dissecting microscope, look for glistening white tubules, which deliver air to the muscles. 8. Identify the reproductive organs that lie on either side of the digestive tract in the abdomen. If your specimen is a male, look for the testis, a coiled, elongated cord containing many tubules. If your specimen is a female, look for the ovary, essentially a collection of parallel tapering tubules containing cigar-shaped eggs. 9. Locate the digestive tract and, in sequence, the crop, a large pouch for storing food (a grasshopper eats grasses); the gastric caeca, digestive glands attached to the stomach; the stomach and the intestine, which continues to the anus; and Malpighian tubules, excretory organs attached to the intestine. Insects secrete a solid nitrogenous waste. Is this an adaptation to life on land? Explain. '-{ e5 . :::I h: ~ u-) C>..U. '-+- ux,t\ i:::--~'"v-e S w~ J...l,i. ;s c.da.y· <.) 10. Work the digestive tract free, and move it to one side. Now identify the salivary glands that extend into the thoracic cavity. 11. Remove the internal organs. Now identify the ventral nerve cord, which is thickened at intervals by ganglia. 12. Remove one side of the exoskeleton covering the head. Identify the brain, which is anterior to the esophagus. Identify the internal structures of the grasshopper. Dorsal Hemocoel artery Crop 0 Stomach vary Heart Vagina Seminal receptacle Ventral Intestine Oviduct (spermatheca) nerve Ganglia Gastric Malpighian cord caeca tubules c ttay.ic,~MeN.;1. LLc