Invertebrate Anatomy OnLine
Copyright 2001 by
This is one of many exercises available from Invertebrate Anatomy OnLine , an Internet laboratory manual for courses in Invertebrate Zoology. Additional exercises, a glossary, and chapters on supplies and laboratory techniques are also available at this site. Terminology and phylogeny used in these exercises correspond to usage in the Invertebrate Zoology textbook by Ruppert, Fox, and Barnes (2004). Hyphenated figure callouts refer to figures in the textbook. Callouts that are not hyphenated refer to figures embedded in the exercise. The glossary includes terms from this textbook as well as the laboratory exercises.
Lophophorata SP, Brachiopoda P, Inarticulata C, Lingulida O, Lingulidae F (Fig 25-35, 9-26)
Lophophorata includes three taxa, Phoronida, Bryozoa, and Brachiopoda, sharing several morphological characteristics. Some zoologists include Kamptozoa in this group. The first three taxa possess a funnel-shaped anterior ring of ciliated tentacles known as a lophophore (Fig 25-2, 25-25A). The lophophore surrounds the mouth and is an upstream collecting system for suspension feeding. Its tentacles are hollow with extensions of a coelomic space thought to be a mesocoel. The gut is U-shaped with the anterior mouth at the center of the lophophore. The anus is also anterior, but is dorsal to the mouth, outside the ring of the lophophore (Fig 25-2A).
The lophophoral tentacles bear two types of cilia. Frontal cilia on the inside face of the tentacles extend into the interior of the lophophore, whereas lateral cilia on the sides of the tentacles extend into the gap between adjacent tentacles. The mouth is at the bottom (apex) of the lophophore funnel and is encircled by the ring of tentacles. The feeding current is generated by the lateral cilia. In lophophorates and many filter feeding deuterostomes (but not Kamptozoa) water enters the open end of the lophophore, moves toward the mouth, and then exits laterally between the tentacles (Fig 25-25A). Food particles are captured on the upstream side of the tentacles and transported to the mouth by the frontal cilia. In cross section the lophophore may be horseshoe-shaped or circular (Fig 25-4).
Lophophorates inhabit a secreted enclosure, tube, shell, or zooecium, that may be organic or mineral. The body is divided into two parts, the mesosome and metasome, each with a coelomic space. The small mesosome is the region of the lophophore and the much larger metasome is the trunk and accounts for most of the body. The tiny anterior epistome is sometimes considered to be a third body region homologous to the protosome of early deuterostomes. Lophophorates are suspension feeders and most are marine but some occur in freshwater.
Brachiopods are suspension feeding, marine, benthic lophophorates in two higher taxa, Inarticulata and Articulata. Brachiopoda is ancient and has a rich fossil record of over 12,000 species although fewer than 350 are living today.
The body, consisting of mesosome and metasome, is enclosed in a calcareous or partly organic bivalve shell with dorsal and ventral valves. The body wall is folded to form a mantle composed of dorsal and ventral lobes enclosing a mantle cavity. The body is enclosed in a shell comprising dorsal and ventral valves secreted by the mantle. A fleshy pedicle attaches the animal to the substratum.
The lophophore, which is the feeding and respiratory organ, is large and coiled into two spiral rows of tentacles. The gut is complete in Inarticulata but ends blindly in Articulata. Excretion is via a pair of large metanephridia. The nervous system consists of a circumesophageal nerve ring from which arise nerves to the body. The hemal system includes a heart, blood channels, and open sinuses. Brachiopods are gonochoric and fertilization is external.
Inarticulata is probably the more primitive, less specialized brachiopod taxon and is thought to be similar to the ancestors of Articulata. Most living brachiopods are articulates, there being only about 50 species of inarticulates. Inarticulates are named for the simplicity of their hinge mechanism, which lacks teeth and is held together only by a complex musculature. The gut is complete and J-shaped. The lophophore is not supported by brachidia. The shell is a combination of calcium phosphate, protein, and chitin. Development is direct with a pelagic juvenile (Fig 25-14E).
The best known inarticulate genera are Lingula and Glottidia of which preserved Lingula are commonly used in laboratory studies of brachiopod anatomy. The genus Lingula is known, virtually unchanged, from fossils extending back at least 400 million years, making it the oldest known animal genus. Lingula is primarily an Indo-Pacific genus and is harvested for human consumption in Japan and Australia.
Lingulid brachiopods inhabit vertical burrows in soft sediments with the anterior end upward at the sediment surface (Fig 25-9A,B). The cilia of the lophophore generate a feeding and respiratory current through the lophophore and mantle cavity.
The exercise is written for preserved Lingula but can be used with living Glottidia if available.
Study a preserved specimen of either Lingula or Glottidia in a small dissecting pan of tapwater using a dissecting microscope. Living specimens are preferable if available and should be dissected in seawater or magnesium chloride.
The bivalve shell encloses most of the soft parts of the body (Fig 1, 25-9A). A long, fleshy pedicle extends from the posterior end of the shell. The shell is composed of two nearly identical valves located on the dorsal and ventral surfaces of the animal. The anterior end is truncate and the posterior end tapers to a point where the pedicle is attached. The apex is the oldest part of the valve and is located on this point. Growth of the young brachiopod occurs anteriorly and laterally from the apex (Fig 25-14E). Numerous concentric growth lines are centered on the apex. The valves move apart at the anterior end to create a narrow opening, known as the gape, through which the feeding and respiratory current passes. In preserved specimens the gape is closed.
A fringe of bristlelike chitinous chaetae emerges from the margins of the valves but the chaetae of preserved specimens are usually broken and are absent or shorter than in life. The edges of the soft mantle lobes can be seen between the margins of the valves. Each valve is secreted by a thin fold of the body wall, the mantle lobe, of which there are two, one for each valve. Like the valves, the mantle lobes are dorsal and ventral. The epithelium of the mantle lobe secretes the valves. The mantle lobes lie immediately inside the valves and enclose a large anterior seawater chamber, the mantle cavity, which is not yet visible.
Look closely at the valves and distinguish between dorsal and ventral. It is important that you make this distinction correctly so that your specimen is not upside down when you dissect it. Several subtle clues can be used to tell you which is dorsal and which ventral. 1. The ventral valve is slightly longer than the dorsal and extends ever so slightly farther anteriorly. Examine the anterior end in side view with the dissecting microscope to determine which is the longer. This can also be detected by sliding your fingernail over the anterior margin of the valves. If you hold the valves tightly together and then slide your fingernail from dorsal to ventral, it will catch on the slight overshoot of the ventral valve. On the other hand, if you are moving the nail from ventral to dorsal, it will not catch. 2. Both valves are arched outwards to accommodate the body but the ventral valve has a slightly higher arch than the dorsal. The difference is best seen by looking end-on at the anterior end. 3. The first 3-4 centimeters of the pedicle arch very slightly dorsally. These three differences are all small but they are consistent and reliable.
Find dorsal, ventral, anterior, posterior, right, and left. Note the bilateral symmetry of the shell. The plane of symmetry divides each valve into right and left. (In contrast, the plane of symmetry of bivalve molluscs passes between right and left valves.)
The articulation between the valves is posterior, at the apex, and in Inarticulata it is simple, without teeth or a hinge mechanism. The hinge of articulates, however, has a complex hinge which is the basis for the taxon name (Fig 25-8C, 25-9D). Inarticulate valves are held together by muscles running from one valve to the other.
The shell of inarticulate brachiopods is composed of chitin, protein, and calcium phosphate and is about 50% organic. The outer surface is covered by a glossy, proteinaceousperiostracum. Because of the high percentage of organic material in the shell, it is relatively flexible and soft. With strong forceps grasp the anterior edge of one valve and bend it gently, noting that it yields slightly.
>1a. Compare the flexibility of this shell with that of an articulate brachiopod, if one is available. Articulate shells are composed of calcium carbonate with little organic material and they are inflexible. <
Figure 1 The inarticulate brachiopod, Lingula, in ventral view. Brach26La.gif
The pedicle (= peduncle) is a long muscular extension of the body used to anchor the animal in its burrow. The epithelium of the posterior end of the pedicle secretes a glue-like mucus that adheres to the sediment in the bottom of the burrow thereby temporarily anchoring the animal. Unlike most articulate brachiopods, inarticulates are not permanently anchored and can change position.
The pedicle emerges from between the narrow posterior ends of the valves but in inarticulates there is no special aperture for it. It contains an evagination of the trunk coelom (metacoel?) and is hollow. In Glottidia and Lingula the connection between the pedicle coelom and the trunk coelom remains open through life.
" With a sharp scalpel make a cross section of the pedicle about 1 mm thick and
about 1 cm from the body. Examine the cut surface with 45X of the dissecting microscope. The pedicle wall is an extension of the body wall and is constructed accordingly (Fig 2). The very thick, transparent, extracellular cuticle is easily seen on the outside. Inside it is a thin layer composed of epidermis and connective tissue but the two cannot be distinguished from each other in gross dissection. The epidermis secretes the cuticle.
Figure 2. Cross section of the pedicle of a preserved Lingula. Brach27L.gif
The thick muscle layer fills most of the interior of the pedicle. The muscle fibers are cross helically wound (fig 6-3E) around the long axis of the pedicle and are anchored in the connective tissue layer. The coelom is usually an inconspicuous canal in the center although sometimes it is large. The mesothelium lining the coelom cannot be seen at this magnification.
" Make a longitudinal section of a 1 cm piece of the pedicle and examine the muscle layer with the dissecting microscope. Note that the orientation of the muscle fibers is longitudinal. Make a wetmount of a thin slice and examine the muscle with the compound microscope.
The body consists of the posterior metasome, or trunk, and the anterior mesosome, which bears the lophophore (Fig 25-10). Two large folds of the metasomal body wall, the dorsal and ventral mantles lobes, extend anteriorly to surround the lophophore and the mantle cavity. The dorsal and ventral mantle lobes are covered by the dorsal and ventral valves.
The first step in the study of the soft anatomy is the removal of the dorsal valve in such a way that all soft parts remain undisturbed and in place in the ventral valve. You must first beabsolutely sure you have correctly identified the dorsal valve as explained above.
The dorsal and ventral valves are held together only by muscles, of which there are several. The dorsal lobe of the mantle underlies the dorsal valve and is in close contact with it. You must separate the dorsal mantle from the dorsal valve without damaging the body, muscles, or mantle. It will also be necessary to separate the muscles from the dorsal valve. Refer now to Figure 3 to determine the location of the three adductor muscles (two anterior and one posterior). Be very careful and proceed as follows.
" To remove the dorsal valve, hold the specimen in one hand and carefully slip the blade of a sharp scalpel through the gape and into the space between the dorsal mantle lobe and the dorsal valve. Keep the blade of the scalpel firmly against the inside surface of the valve and use it to push (rather than cut) the mantle away from the shell and to cut the three adductor muscles where they attach to the shell. Separate the dorsal valve from the dorsal mantle lobe and body by cutting the several additional muscles attached to it without damaging the mantle lobe or the body. Gently lift the dorsal valve and remove it. The body should remain in the ventral valve. The dorsal mantle lobe may have sustained some damage during this procedure.
Look at the apices of the valves with magnification and note that there is no special hinge mechanism. There is an inconspicuous notch for the exit of the pedicle.
>1b. Examine the articulation of the shell of an articulate brachiopod. Note the elaborate hinge and compare it with the simple articulation of Lingula. <
>1c. Place the dorsal valve in a dish of bleach and examine it after 24 hours. Bleach oxidizes organic compounds but has no effect on minerals such as calcium phosphate and calcium carbonate. Are the results consistent with the statement that much of the shell is organic? Place another valve in weak (8%) HCl. Observe and explain the results. <
Spend a few moments identifying the major organs on the dorsal surface of the body for use later as landmarks. The anterior third of the space inside the shell is occupied by the mantle cavity which is hidden by a thin, sheet of tissue, the dorsal mantle lobe. (The mantle lobe may have been destroyed or damaged during the removal of the dorsal valve.)
Lift the anterior edge of the dorsal mantle lobe to reveal the mantle cavity and lophophore (Fig. 3). The large lophophore, with its fringe of abundant small tentacles is in the mantle cavity and is easy to recognize.
Figure 3. Dorsal dissection of a preserved Lingula. The dorsal valve, dorsal mantle lobe and most of the dorsal body wall have been removed. Most of the chaetae have been omitted. Brach28La.gif
Near the middle of the animal is a large triangular muscle cone consisting of muscle and connective tissue. Other obvious features on the dorsal surface include the two anterior adductor muscles and the single posterior adductor muscle. The anterior adductor muscles are in the muscle cone.
The large, glandular, greenish digestive cecum is posterior to the anterior adductor muscles. The gonads occupy much of the space in the posterior part of the body.
Body Wall and Coelom
The body wall over most of the dorsal surface of the body is very thin and transparent. It is inconspicuous and may have been damaged or lost when the valve was removed. The postero-lateral edges of the body wall, on each side of the apex, however, are reinforced with connective tissue that forms very noticeable opaque, white, oval patches. No matter how thin and inconspicuous the body wall, it separates the coelom inside from the external environment.
Two regions of the body are present as well as a tiny epistome, which you will see later. The anterior region, or mesosome, is the region of the lophophore and its coelomic cavity is the lophophore coelom (= mesocoel). The posterior two thirds of the body is the trunk (= metasome), whose cavity is the trunk coelom (= metacoel) (Fig 3, 25-10). Most of the internal space in the animal is trunk coelom. The trunk coelom extends into the pedicle and mantle lobes and is divided into anterior and posterior regions by a transverse septum located immediately posterior to the anterior adductor muscles. The trunk coelom is partitioned by dorsal, ventral, and two lateral mesenteries.
Mantle and Mantle Cavity
The mantle cavity contains the lophophore and is bounded dorsally and ventrally by the two mantle lobes, which are folds of the anterior trunk body wall. As folds, they consist of twolayers of body wall with a narrow coelomic space between them. Find the dorsal mantle lobe the similar ventral mantle lobe. Part of the latter can be seen on the inner surface of the ventral valve (Fig 3). The trunk coelom extends into each mantle lobe where proliferation of connective tissue reduces it to a set of tubelike mantle canals (Fig 3).
Each mantle lobe has a fringe of chitinous bristles, or chaetae, which protect the gape and mantle cavity from the intrusion of sediment. Chaetae fringe the right, left, and anterior edges of the valves where they form two siphon-like inhalant channels and one median exhalant channel, called pseudosiphons (Fig 1, 25-9A,B).
The feeding and respiratory current enters the anterolateral corners of the mantle cavity via the two inhalant pseudosiphons, formed of the relatively longer and thicker chaetae in those regions. The water then flows through the lophophore where food particles are captured and transported to the mouth by cilia. Once past this filter, the currents merge on the midline and flow anteriorly to exit the mantle cavity via a single median exhalant pseudosiphon, which is also formed of chaetae.
" Remove any remains of the dorsal mantle lobe by snipping its connections with the body noting that it extends along the edges of the body to its posterior end.
>1d. Make a wetmount of a large piece of mantle lobe. Be sure you include some of the margin and place the inner, striped surface UP on the slide. Be sure it is not folded on itself. Examine the preparation with scanning (40X) and low (100X) power of the compound microscope. The branched mantle canals occupy most of the lobe. Look at the chitinous chaetae on the mantle margins, noting that they are fibrous and jointed. <
Lingula and Glottidia, like almost all brachiopods, are gonochoric. The paired dorsal and ventral gonads are located retromesothelialy, just outside the posterior part of the coelom. The dorsal gonads occupy most of the dorsal space posterior to the digestive cecum (Fig 3) and the ventral gonads occupy a similar position on the other side of the body. In preservedLingula, the ovary is orange or brown and has a fine, lobulated texture. The testis is cream or pale yellow and has a coarser lobed texture. The lobes resemble eggs nut are not, of course.
When ripe, gametes break through the mesothelium and enter the coelom. They then enter the metanephridia and are shed into the mantle cavity via the nephridiopore. They exit the mantle cavity and fertilization takes place externally, in the sea.
>1e. Remove a small piece of the gonad, place it on a slide, tease it apart, and affix a supported coverslip. Examine the preparation with a compound microscope and look for gametes. Eggs are large, yolky spheres with a conspicuous nucleus. Sperm are much smaller and have long flagella. <
The brachiopod lophophore consists of two spiral arms, or brachia, connected with each other at the midline (Fig 3, 4, 25-10A). The two coiled brachia occupy most of the space in the mantle cavity.
Figure 4. Dorsal surface of the anterior body of Lingula with the brachia removed. Brach29L.gif
Lift the lophophore gently so you can see its ventral surface and appreciate the extent of coiling of the brachia. The surface of each brachium bears a brachial fold, brachial groove, and row of hollow ciliated tentacles. The brachial fold is a thin, narrow sheet of tissue covering the base of the tentacles (Figs 3, 4). The space between it and the tentacles is the deep, narrowbrachial groove. Each of these extends along the entire length of the lophophore and coils along its brachium. As you look at the intact left brachium from your dorsal vantage point, you can see a part of the left brachial fold extending obliquely across the base of the tentacles that are visible to you. Lift its free edge with the microneedle to demonstrate to yourself that it is a thin sheet of tissue.
" Use fine scissors to cut across the axis of one brachium at its base and remove it. Look at the cut surface (it is a cross section) of the excised brachium with the dissecting microscope (Fig 4). The axis is hollow and contains muscles, blood vessels, nerves, and two coelomic spaces but only the brachial muscle and lophophoral coelom are visible in the cross section. Branches of the lophophoral coelom extend into the tentacles. The lophophoral coelom is thought by some to be homologous to the mesocoel. Find the tentacles on the cross section (Fig 4). Find openings from the lophophoral coelom into the tentacles. In the lingulids the lophophore bears a single row of tentacles rather than the double row found in most lophophorates. The row of tentacles thus does not close on itself to form a ring and hence does not actually encircle the mouth.
>1f. If living specimens are available in the laboratory, place one in a large culture dish of seawater and give it time to become accustomed to its surroundings. It may relax its muscles and permit its valves to gape. Place a small amount of carmine/seawater suspension in the water in front of the gape and watch the motion of the suspended particles. Try to identify the currents at the inhalant and exhalant pseudosiphons. Living specimens in the laboratory may glue the posterior end of the pedicle to the dish. <
" Remove the remaining brachium to give an unobstructed view of the midline at the anterior end. Hold the muscle cone out of the way with your fingers so you can see the center of the lophophore between the stumps of the brachia (Fig 4). The small anterior projection on the midline is the epistome. It is dorsal to the mouth. Do not confuse the epistome with the far larger muscle cone. The brachial fold and row of tentacles cross the midline ventral to the epistome.
The mouth is an inconspicuous transverse slit lying on the midline in the brachial groove (between the brachial fold and the tentacles). The muscle cone, epistome, and brachial fold must be folded up and held out of the way before you can see the mouth under them. Lift the specimen above the pan and hold it vertically on the stage of the dissecting microscope with the anterior end pointed up, toward you.
The inconspicuous, median, longitudinal hump on the dorsal surface above the mouth reveals the position of the short esophagus, which is just below the surface.
" Abandon the anterior end of the gut for the moment and find the intestine in the posterior trunk coelom (Fig 3). With fine scissors cut away the tough, white, connective tissue of the posterior lateral body wall and carefully remove the dorsal gonad but leave the digestive ceca intact.
The intestine emerges from beneath the posterior edge of the digestive cecum, extends almost to the posterior adductor muscle, makes two loops, and then extends anteriorly to the right (Fig 3). It disappears under a large flat muscle (right lateral muscle) and is lost from view. It eventually ends at the anus at the top of the tiny anal papilla on the right edge of the body (Fig 3). The anus opens into the right side of the mantle cavity.
The digestive ceca are stomach diverticula occupying most of the middle region of the trunk coelom (Fig 3). They are divided into anterior and posterior lobes by the transverse septum. These lobes connect to the stomach region of the gut by ducts.
" Carefully lift each lobe of the digestive ceca with fine forceps to reveal (without breaking) the duct connecting it with the stomach. Cut the duct, and remove the cecum. Remove the two posterior lobes first. Watch for the heart as you remove the digestive ceca. The stomach begins between the two anterior adductor muscles, extends posteriorly to penetrate the transverse septum, and becomes the intestine.
The tiny, inconspicuous, elongate, whitish dorsal blood vessel and heart lie in the mesentery dorsal to the stomach and immediately posterior to the transverse septum. They are difficult to reveal.
" Without damaging the musculature, follow the stomach anteriorly to its connection with the esophagus.
In all brachiopods the valve musculature is responsible for holding the valves together as well as for closing them. In the absence of a rigid hinge mechanism, the valve musculature of inarticulates must also maintain the proper alignment between the valves and move them from side to side. As a consequence, it is more complex than in articulates and the musculature of lingulids is the most complicated of any brachiopod.
The paired anterior adductor muscles in the middle of the body extend from the center of one valve straight through the body to the center of the other valve. The single posterior adductor muscle does the same at the extreme posterior end of the body. The posterior adductor appears to be on the midline but if you look closely you will see that it is displaced a little to the left. The adductor muscles draw the valves together and close the gape. Several other muscles are associated with the valves and can be studied as an optional exercise.
>1g. The right and left lateral muscles originate on the midline of the dorsal valve and on each other, as part of the muscle cone. They pass obliquely to the edge of the ventral valve and then extend posteriorly to insert on the posterior midline of the ventral valve (Fig 3). You saw and cut between them earlier when you were tracing the stomach to its connection with the esophagus.
Remove or reflect the intestine and mesenteries so you can see the large muscles in the posterior body cavity. During the dissection of these muscles you must be careful that you do not damage any tissues other than the muscles. The three, large, asymmetric muscle bands you see in the posterior body cavity are the median oblique muscles. The right median oblique is a single broad, flat muscle that extends from the right edge of the dorsal valve (Fig 3) across the body to a position on the left side of the midline of the ventral valve. The two left median oblique muscles occupy the equivalent position on the left side (Fig 3). Both arise on the left edge of the dorsal valve and run to the right of the midline of the ventral valve. Ventrally one runs anterior to the right median oblique and the other runs posterior to it.
Carefully detach the loose connections of the median oblique muscles on the edges of the body. Remember that you have removed the dorsal valve and in doing so have already cut the attachments of these muscles to it. Do not damage the large metanephridia lying ventral to the posterior edge of the muscles.
Ventral to the anterior edge of the median obliques are two more pairs of oblique muscles. Unlike the median obliques, these are symmetric. The first (dorsalmost) pair is the slenderinternal obliques, one on the right and one on the left (Fig 3). They arise, beside the median obliques, on the edge of the dorsal valve and extend anteriorly medial to the two anterior adductor muscles to insert on the ventral valve.
Ventral to the internal obliques is the last pair of these muscles, the external obliques. Like the internal obliques they arise laterally beside the median obliques on the dorsal valve and insert on the ventral valve. Unlike the internal obliques, their insertion is lateral, rather than medial, to the anterior adductors. They arise with the median and internal obliques on the dorsal valve.
This is the full complement of valve muscles. Together they are capable a repertoire of complex valve movements of the including slicing the valves past each other like the blades of scissors to dig into the sediment (Fig 25-11A,B). <
>1h. If living Glottidia are available, put one in a dish of seawater over silty sand. Watch the activity of the valves in the digging process. <
Other muscles are present in the body wall, lophophore, mantle, and pedicle. The mantle chaetae are supplied with several small muscles each and their motion is precisely controlled. It has been reported that the mantle chaetae propel the animal across the sediment surface.
The contractile heart is part of an inconspicuous dorsal, longitudinal blood vessel lying dorsal to the stomach. This vessel sends branches to the lophophore, gut, mantle lobes, nephridia, and gonads. The blood vessels are unlined spaces in the connective tissue leading to blood sinuses. Study of the hemal system is not feasible in these animals. Careful observers, however, may notice fine, transparent blood vessels supplying the oblique and lateral muscles.
A large metanephridium lies on each side of the body cavity with their proximal ends protruding from under the muscles in the trunk coelom. Reflect and pin the right ends of these bands of muscle aside to expose most of the right metanephridium (Fig 3). It is long, flat, and much of it is bright orange. Its posterior part is a white, funnel-like nephrostome with ruffled walls. The nephrostome opens from the trunk coelom into the wide, flat, orange tubular portion of the nephridium. This portion tapers as it runs anteriorly to open into the mantle cavity via a nephridiopore on the anterior body wall.
" Remove the right nephridium to expose the terminal portion of the intestine, cutting muscles as necessary to trace the intestine to the anus.
The nervous system consists of a circumesophageal nerve ring with nerve cords to the body, including the pedicle. Dissection of the nervous system will not be attempted. Lingulids are light-sensitive and although the photosensitive tissue has not been identified, the dark brownish pigment around the mantle cavity may be involved. The chaetae are thought to be mechanoreceptors.
Beyers HG . 1886. A study of the structure of Lingula (Glottidia) pyramidata Stim. (Dall). Studies Biol. Lab. Johns Hopkins Univ., 3:227-265, pls. 14-17.
Chuang SH. 1959. The structure and function of the alimentary canal in Lingula unguis (L.) (Brachiopoda). Proc. Zool. Soc. London, 132:283-311.
Hyman LH . 1959. The Invertebrates: Smaller Coelomate Groups, vol. V. McGraw-Hill, New York, 783p.
Parker SP. (ed). 1982. Synopsis and Classification of Living Organisms, vol. 2. McGraw-Hill, New York. 1232p.
Rudwick MJS. 1970. Living and Fossil Brachiopods. Hutchinson University Library, London. 199p.
Ruppert EE, Fox RS, Barnes RB. 2004. Invertebrate Zoology, A functional evolutionary approach, 7 th ed. Brooks Cole Thomson, Belmont CA. 963 pp.
Williams A, Rowell AJ. 1965. Brachiopod anatomy, pp. H6-H57 in Moore RC (ed), Treatise on invertebrate paleontology, Part H, Brachiopoda, vol 1. Geological Society of America and University of Kansas Press, Lawrence, KS.
Slides and coverslips
Small dissecting pan
Preserved or living Lingula or Glottidia
Dissecting set with microdissecting tools
Articulate brachiopod shell
# 1 stainless steel insect pins