"Imagination is everything.
It is the preview of life's upcoming attractions."

    Albert Einstein (1879-1955)

     German-born American physicist, Nobel Prize for Physics in 1921

 


  Neocyclotid land snail, Cycladamsia seminudum. Windsor, north-central Jamaica.

 


 

The Silent Sliders

 

    The "invertebrates" are an artificial aggregation of animals that encompasses widely different phyla and comprises the bulk - in terms of both number of species and of individuals -  of the animal biomass in every ecosystem on Earth. Insects, arachnids, crustaceans, onycophorans, mollusks, earthworms, rotipherans, nematodes, centipedes, millipedes, and others inhabit the tropics of the World, perhaps by the millions of species. The largest higher group alone, Insecta, includes more species than all others - plant and animal - put together.

 

    The soils of the tropics are rife with small invertebrates of all sorts. While most of them are tiny, even microscopic, their lives are carried out in a world that is very complex in its own scale. Hordes of pillbugs, collembolla, earthworms, slugs, insect larvae, and others are the herbivores and carrion-eaters of this scaled-down universe. Its predators and parasites come in the shape of flatworms, nematodes, leeches, pseudoscorpions, mites, ants, tiny wasps and flies and their larvae, and many others.

 

    Even more complex are the invertebrate faunas that live above ground, on the vegetation and to the highest canopies of the rain forests. Immense numbers of species which shapes, colors, and lifestyles defy description await discovery high above human eyes, and are beyond the reach of the average person.


PHYLUM NEMATODA: ROUNDWORMS

 

    Only slightly more advanced than flatworms, roundworms are among the most abundant organisms on Earth, both in terms of species and in the sheer number of individuals. Astronomical hordes of them swarm in most habitats that have a minimum of available water, from the deepest oceanic abysses to alpine environments, and especially in the soils and leaf litters of the tropics. In humid terrestrial habitats, their combined biomass may be staggering, far outweighing that of all macro-organisms combined. This is remarkable given the fact that, by far, most species are microscopic. A rather few species are large enough to be noticeable to the naked eye, and one (another parasite of whales) is more than 10 meters long.

 

    Some nematodes are important parasites of plants and animals, as well as of man. Others feed on dead, decaying tissues, or on bacteria and protozoans. Still other species are commensal symbionts that live in the guts of higher animals.

 

A nematode on leaf litter, species undetermined. Neiba Mountains, south-central Dominican Republic, Hispaniola.


PHYLUM PLATYHELMINTHES: FLATWORMS

 

    The term "worm" has no systematic value whatsoever. Basically, any elongated invertebrate can be called a "worm", regardless if it is or not related to similar creatures. However, two of the most primitive types of organisms receive that common name: flatworms (Phylum Platyhelminthes) and roundworms (nematodes, Phylum Nematoda).

 

    These two groups are among the simplest among the Bilateria, animals which bodies can be longitudinally and dorsoventrally divided into halves that are mirror images of one another (as is our own case).

 

    Flat- and roundworms lack a "coeloma", an internal body cavity (other than the gut itself) where the viscera are located. They lack respiratory, circulatory, and digestive systems. Oxygen is absorbed through the external epithelial cells, food is absorbed directly through their internal bodily tissues, and nutrient molecules are spread straight through cells through extracellular ("interstitial") fluids. Another trait peculiar to both, and which differentiates them from every other wormlike group, is that they lack true segmentation in their bodies, which are mainly solid, uninterrupted rods of muscular tissue.

 

Flatworms (phylum Platyhelminthes) are the most primitive of bilaterally symmetrical organisms.

Most members of the group are aquatic denizens of freshwater or marine habitats.

This terrestrial planarian (class Turbellaria)  is Bipalium kewense. Photographed in Carolina, north-eastern Puerto Rico.

This species is Cosmopolitan, after being shipped around Earth on plant pots.

Its place of origin is not known for certain, but it could be eastern Asia.

 

Turbellarian flatworm, species undetermined. El Verde Biological Station, north-eastern Puerto Rico.

 

    Among platyhelmynthes, and unlike the many parasitic cestodes ("tapeworms") and trematodes (flukes), most turbellarians (planarians), are aquatic, living in freshwater ponds and streams, or at sea. Also, most are carnivores. Terrestrial species feed on earthworms and other soft-bodied invertebrates. A predatory flatworm envelop its prey with their its body, immobilizes them with mucus, and then protracts what resembles a pliable tube from its underside. This organ dissolves its victims' tissues with the use of digestive enzymes. The resulting "soup" is suctioned through the tube and then absorbed directly through the inner bodily cells in an amoeboid fashion. The mouth through which this protractible pharynx is extruded also serves as the anus.



Turbellarian flatworm, species undetermined. Cambalache State Forest, northern Puerto Rico.
(Photograph courtesy of Mr. Alfredo Colon Archilla).


Trematode flatworm, species undetermined, parasitic under the skin of a xenodontine snake, Borikenophis portoricensis portoricensis.

Fort Buchanan, Guaynabo, north-eastern Puerto Rico.

 

    Because, unlike higher metazoans, it lacks any complex organs located in specific parts of the body sometimes a flatworm severed into two or more pieces will result into as many complete individuals, after each piece regenerates any missing parts.


PHYLUM NEMERTEA: RIBBONWORMS


    These organisms seem to be related to flatworms, and most are marine or freshwater in habits. A few species are terrestrial and predatory or commensal on regards to other animals. They possess a proboscis ahead of the mouth, armed with a stylet with which they impale their prey. One marine species species, Lineus longissimus, is perhaps the longest metazoan known, reaching more than 40 meters in length.


Nemertine worm, species undetermined. Crown Mountain, central Saint Thomas, United States Virgin Islands.

 

PHYLUM MOLLUSCA: MOLLUSKS

 

    All mollusks have a "mantle", a dorsal body wall that encircles the entire visceral cavity. Interestingly, the members of this group do not have a segmented bodily pattern, which is the rule among most other metazoan phyla. In spite of being a very ancient group of animals some molluscs possess the most complex nervous systems among invertebrates.

 

    This phylum is second only to arthropods in the number of species it contains. The great majority of mollusks are aquatic and, of such, most are marine. Its classes include, among others, snails and slugs (Gastropoda), clams and oysters (Bivalvia), chitons (Polyplacophora), and octopi, squid, and nautili (Cephalopoda). Among these last is the largest known invertebrate, Mesonychoteuthis hamiltoni, a squid perhaps longer than 20 meters, including its twin tentacles.

 

CLASS GASTROPODA: SNAILS

 

    The one thing that all gastropods (both terrestrial and aquatic) have in common is their primary means of locomotion. They possess a muscular "foot" on their undersides that propel them through undulations as they glide over a film of mucus. Hence comes their name, "gaster-pous": "it that has a foot on its stomach". Snails are well known for the slow, somnanbulant way they move about.



The underside of a land snail, Zophos concolor, (family Haplotrematidae), shows its "foot".

Florida, central Puerto Rico.



Many land snails possess two pairs of head tentacles. The upper ones bear eyes, while the lower ones are chemical receptors.
  Pleurodontid snail, Caracolus carocolla. El Verde Field Station, north-eastern Puerto Rico.

 

    Only bivalves and gastropods have colonized freshwater, and both of these groups are found in West Indian rivers, streams, and lakes. However, only gastropods of the subclass Pulmonata have also invaded land. Snails and slugs (these last are simply snails that evolved to loose their shells) are especially common in the damp environment of humid and rain forests. Many beautiful species are found especially in Cuba and Hispaniola (especially those of the genera Liguus and Polymita as well as some Dentillaria and Caracolus), but all the Antillean insular banks have endemic representatives of this group.

 

    Snails have secondarily and partially lost their bilateral symmetry. The body of the animal is encased in a spiral shell (secreted, as in all shelled mollusks, by the mantle) and, as the animal matures from the larval stage to adulthood, the whole body twists about 180 degrees. Hence, the anus ends up facing forward, above and behind the head. Slugs better preserve bilateral symmetry since, lacking a shell, their bodies are not twisted into a spiral.

 

    Most species of terrestrial snails are hermaphrodites, and mutually inseminate during their sexual encounters. During mating, some species insert a sort of either calcareous "dart" or a spermatophore into each other. It is believed that the object contains hormones that "activate" the female gonads, making them receptive to sperm.

 

Pleurodontid snails, probably Zachrysia provisoria, during mating. Notice the spermatophore that one individual crawls away with.

Barrenspot, central Saint Croix, United States Virgin Islands. Introduced from Cuba.



Mating pair of Gaeotis nigrolineata. El Yunque National Forest, north-eastern Puerto Rico.


ORDER MESOGASTROPODA

 

    This group contains a number of species whose closest affinities lie in Earth's oceans. They can be told apart from other land snails by the presence of an operculum, a horny plate attached to the back of the foot that closes the entrance to the shell when the animals hides within it. Unlike the more advanced stylommatophores, their eyes are not borne at the ends of long, tentacle-like stalks, but on the sides of their heads.

 

Family Megalomastomidae

 

Megalomastomid snails, Megalomastoma croceum, (family Cyclophoridae). Florida, central Puerto Rico.

The first photograph shows an adult and a juvenile.

 

Megalomastomid snail, Farcimoides orbignyi. Ebano Verde Nature Reserve, central Dominican Republic, Hispaniola.

(Photograph courtesy of Dr. Jozef Grego).

 

ORDER NEOTAENIOGLOSSA

 

    This also an order whose majority of members are marine. A number of species have invaded land and, like those of the previous order, have opercula to close their shells when under threat or while resting.

 

Family Annulariidae

 

    This family is best represented in Central America and the Caribbean region. Several similar genera are found in the islands of the Caribbean, particularly in the Greater Antilles. They are usually small and have conical but apically truncated shells.

 

Annulariid snail, Colobostylus bronnii. Windsor, north-central Jamaica.

 

Annulariid snail, possibly Parachondria fascia. Blue and John Crow Mountains National Park, east-central Jamaica.

These and similar species show and operculum that seals the shell when the animal retreats inside.



Annulariid snails, probably Choanopoma sp.
First photograph: El Yunque National Forest, north-eastern Puerto Rico.
Second photograph: Ciales, central Puerto Rico.



Annulariid snails, Chondropoma riisei. Florida, central Puerto Rico.
Some species in this family heng themselves from thin lines of mucus, which solidifies upon contact with air.
This way, thay can rest while remaining safe from small predators.


Annulariid snail, species undetermined. Near Duverge, south-western Dominican Republic, Hispaniola.


ORDER NERITOIDEA: NERITES

 

    This is the third group of mainly marine and freshwater snails some of which members have secondarily adapted to life in humid terrestrial habitats. Only the next family is represented in this region.

 

Family Helicinidae

 

    This group has a disjunct distribution. In the Americas they live only in the Caribbean islands and some regions in the continental Neotropics. Elsewhere, they can be found in some oceanic islands in the Indo-Pacific Ocean as well as in some areas of Asia and Australia. They are small to medium-sized snails, some with gaudy colors to their shells. They seem to represent a secondary evolutionary invasion of a terrestrial habitat, after that of more typical and "ancient" land snails. Being more tied to water than other snails, they frequently inhabit damp montane forests.

 

Helicina gabbi, (family Helicinidae).  Ebano Verde Scientific Reserve, central Dominican Republic, Hispaniola.

(Photograph courtesy of Dr. Jozef Grego).

 

Helicina phasianella. Florida, central Puerto Rico.
 


Helicina iris. Macaya National Park, south-western Haiti, Hispaniola.

(Photograph courtesy of Mr. Eladio M. Fernandez).


Helicina fasciata.
First two photographs: Mount Scenery, central Saba, Lesser Antilles.
Third photograph: near Nevis Peak, central Nevis, Lesser Antilles.


Helicina occidentalis. Vermont Nature Reserve, northern Saint Vincent, Lesser Antilles.


Helicina platychila. Mount Scenery, central Saba, Lesser Antilles.


Helicina adpersa. Guanahacabibes Peninsula, western Cuba.
(Photograph courtesy of Mr. Joseph Burgess).


Helicina sp. Pic du Paradis, central Saint Martin, Lesser Antilles.

Helicinid snail, probably, Helicina sp. Kenscoff, south-eastern Haiti, Hispaniola.

(Photograph courtesy of Mr. Eladio M. Fernandez).



Helicina sp. Florida, central Puerto Rico.


Viana regina. Viņales, western Cuba.
(Photograph courtesy of Mr. Joseph Burgess).


Alcadia viridis. Macaya National Park, south-western Haiti, Hispaniola.

(Photograph courtesy of Mr. Eladio M. Fernandez).

 

Alcadia alta. El Yunque National Forest, north-eastern Puerto Rico.

(Photograph courtesy of Mr. Alfredo Colon Archilla).



Helicinid snail, possibly Alcadia sp. Windsor, north-central Jamaica.



Helicinid snail, species undetermined. Carite State Forest, east-central Puerto Rico.



  Eutrochatella globosa. Jaragua National Park, south-western Dominican Republic, Hispaniola.


ORDER STYLOMMATOPHORA: PULMONATES

 

    This order comprises the vast majority of terrestrial mollusks on planet Earth. They are the "pulmonates", snails and slugs adapted to habitually breath gaseous oxygen by means of gills adapted to become primitive but functional lungs. They all present the morphological character of having their eyes at the end of retractable stalks.

 

Family Amphibulimidae

 

    This family is an Antillean endemic, represented in the region by Amphibulina and Plekocheilus, from the Lesser Antilles, and Gaeotis from Puerto Rico. They are mostly snails of wet tropical forests, many with reduced shells. Indeed, some seem to be evolving into slugs.

 

Amphibulina patula dominicensis. Eggleston, south-central Dominica, Lesser Antilles.


Gaeotis nigrolineata. Carite State Forest, east-central Puerto Rico.



A helicinid snail preys on the eggs of Gaeotis nigrolineata. Carite State Forest, east-central Puerto Rico.


Plekocheilus aurissileni. Vermont Nature Reserve, south-western Saint Vincent, Saint Vincent and the Grenadines, Lesser Antilles.

Family Bulimulidae

    The bulimulids are a family of medium-sized to large snails, mainly tropical and sub-tropical in their distribution. They are among the most easily seen land snails in the West Indies, perhaps after the pleurodontids. Some species possess shells that are quite attractive in their coloration.

Bulimulus guadalupensis, (family Bulimulidae). Carolina, north-eastern Puerto Rico.



Drymaeus virgulatus.

First two photographs: Guanica State Forest, south-western Puerto Rico.

Last two photographs: Florida, central Puerto Rico.



  Drymaeus virgulatus (introduced). Gilboa Hill, northern Saint Eustatius, Lesser Antilles.



Drymaeus mutifasciatus christophori. North-western Saint Christopher, Lesser Antilles.

 

Drymaeus sallei. Formond, south-western Haiti, Hispaniola.

(First photograph courtesy of Dr. Jozef Grego. Second photograph courtesy of Mr. Eladio M. Fernandez).

 


Liguus virgineus. Jaragua National Park, south-western Dominican Republic, Hispaniola.



Liguus sp. Hicacos Peninsula, north-western Cuba.
(Photograph courtesy of Mr. Joseph Burgess).



Liguus vittatus, endemic to the xeric forests of the Desembarco del Granma National Park, south-eastern Cuba.
(Photographs courtesy of Dr. Julio Genaro.)


Family Cerionidae

 

    Due to their soft and mucous skin that looses water so easily, most snails are denizens of humid areas. The mesic and hydric forests of the Antilles have the highest number of species in the Caribbean region. However, some taxa are adapted to live in xeric areas, even deserts. Almost invariably, these species enter into aestivation during the hottest and driest months of the year. The mollusks will seal the entrance to their shells with mucus that hardens to a papery consistence and which prevents water loss. They become active only during the rather short periods of rain that occur every year in these regions. Then they feed, mate, and lay eggs as soon as possible, during the short periods when the ambient humidity stays high. Once the rainy season is over, they will again resume their inactive stage, often until the following year. This capacity to enter into a dormant stage during their life-cycle (shared by many organisms that live in such areas) is called "xerobiosis", and such organisms are called "xerobionts".

 

    This trait is especially noticeable in members of the genus Cerion, found in southern Florida and the Greater Antillean and Bahamian insular banks.

 

Puerto Rican peanut snails, Cerion striatella.

First photograph: Cabo Rojo State Forest, south-western Puerto Rico.

Second photograph: Guanica State Forest, south-western Puerto Rico.

This species belongs to one of several Antillean genera highly adapted to xeric forest and desert habitats.

The genus of about 600 species is endemic to the Caribbean region.

 

During the infrequent rains that fall in their xeric habitat, Cerion striatella snails

become active, and use their time well in order to feed and mate.

Guanica State Forest, south-western Puerto Rico.


Family Clausiliidae

 

    The West Indian members of this family are small snails with elongated shells. They feed mostly on thin layers of microscopic algae and fungi growing on exposed surfaces in rain and cloud forests. The name of the family derives from the Latin "clausilium", which in their case defines a calcareous structure that serves a door with which the animal seals itself inside its shell. The structure fits into grooves in the shell, and closes tightly at the will of the animal. The clausilium is analogous to the "operculum" of some marine snails and their terrestrial relatives (like helicinids). Thus, it is a structure with a different origin but with fulfills the same function. (True opercula are unknown in pulmonate snails).

 


Nenia tridens. Carite State Forest, east-central Puerto Rico.

 

 Nenia tridens feeding on the film of algae on the shell of a much larger Caracolus carocolla snail.

El Yunque National Forest, north-eastern Puerto Rico.

 

Nenisca franzi. Massif de la Hotte, south-western Haiti, Hispaniola.

(Photograph courtesy of Mr. Eladio M. Fernandez).

 

Family Haplotrematidae

 

    These is an American family. Most members are rather small and are inhabitants of forested or, at least rather humid regions. The genera Austroseletines, Zophos, and others in the Caribbean are mostly found under rocks and debris in mesis forests.

 

Zophos concolor. Ciales, central Puerto Rico.


Family Helminthoglyptidae

 

    This group includes some of the most colorful land snails in the World, the Polymita of Cuba eastern Cuba. Highly prized by shell collectors, several populations are seriously endangered at this point.

 


Euclastaria musicola. Guanica State Forest, south-western Puerto Rico.



Plagioptycha sp. San Rafael, southern Dominican Republic, Hispaniola.

 


Cepolis definita. Jaragua National Park, south-western Dominican Republic, Hispaniola.

(Photograph courtesy of Mr. Pedro Genaro Rodriguez).



Levicepolis riveroi. Guilarte State Forest, west-central Puerto Rico.
 

Polymita picta, (family Helminthoglyptidae). Baracoa, eastern Cuba.

(Photograph courtesy of Mr. Eladio M. Fernandez).

 

Polymita muscarum. Velsaco, Holguin Provice, north-eastern Cuba.

(Photograph courtesy of Mr. David Ortiz Martinez).


Family Oleacinidae

 

    This taxon includes some predatory species. Their thin shells seem to be made of glass or porcelain, and the majority of species appear to be terrestrial.

 

Oleacina voluta. Masiff de la Hotte, south-western Haiti, Hispaniola.

(Photograph courtesy of Mr. Eladio M. Fernandez).

Oleacinid snail, possibly Oleacina sp. Near Pie Pol, Bahoruco Mountains, south-western Dominican Republic, Hispaniola.

 


Boriquena glabra. El Yunque National Forest, north-eastern Puerto Rico.
This individual cleans its own shell with its radula.

 


Vagavarix sp. Ciales, central Puerto Rico.


Family Pleurodontidae

 

    Until rather recently, this family was considered one with Camaenidae, today treated as an Old World taxon. Pleurodontids are perhaps the most commonly encountered land snails in the West Indian islands. Because some members of the family can be quite large they served as a source of protein for the pre-Colombian Antillean cultures. They broken shells a often found in Caribbean archaeological sites.

 


The calcareous eggs of the pleurodontid snail, Parthena acutangula. El Yunque National Forest, north-eastern Puerto Rico.

 

    On several islands, terrestrial snails of the genera Caracolus, Dentillaria, Pleurodonte and Polydontes are the most obvious land mollusks. Sometimes found by the hundreds or thousands per acre, they feed on leaves and on the film of microscopic algae growing on tree trunks and rocks. It is interesting to note that despite the abundance of these and similar species in the Antilles, very few predators specialize in the consumption of snails have evolved in this region. The only exceptions seem to be the Chondrohierax and Rhostramus kites present in some of the Greater and Lesser Antilles. These hawks possess strongly hooked bills adapted to extract the soft flesh of snails out of their shells.

 


Pleurodontid snail (eastern Puerto Rican race, Caracolus marginella marginella). Rio Grande, north-eastern Puerto Rico.

 


Pleurodontid snail (western Puerto Rican race, Caracolus marginella mayaguezi). El Rosario, south-western Puerto Rico.



Caracolus carocolla, feeding on dead mosses and fallen fruit.

First photograph: El Yunque National Forest, north-eastern Puerto Rico.

Second photograph: Fort Buchanan, Guaynabo, north-eastern Puerto Rico.

 


Caracolus excellens. Santo Domingo, southern Dominican Republic, Hispaniola.



Dentillaria amabilis. Windsor, north-central Jamaica.



Dentellaria sloaneana. Windsor, north-central Jamaica.



  Granodomus lima lima. Florida, central Puerto Rico.

 


  Granodomus lima asperula. Mount Sage, west-central Tortola, British Virgin Islands.

 


Luquilla luquillensis. El Yunque National Forest, north-eastern Puerto Rico.

This monotypic genus is endemic to the Luquillo Mountain Range, which gives it its specific epithet.


  Hispaniolana obliterata. Near Formond, south-western Haiti, Hispaniola.
The genus is endemic to the Hispaniolan insular bank

(Photograph courtesy of Mr. Eladio M. Fernandez).

 


  Hispaniolana dominicensis. Los Haitises National Park, north-eastern Dominican Republic, Hispaniola.



An adult Parthena acutangula snail has a washed-out shell. El Yunque National Forest, north-eastern Puerto Rico.

These snails are the largest terrestrial gastropods in the Puerto Rican bank, and the genus is endemic to the island's mesic forests.



  Pleurodonte orbiculata. Gros Islet, north-western Saint Lucia, Lesser Antilles.



Pleurodonte guadeloupensis, juvenile. Pic du Paradis, central Saint Martin, Lesser Antilles.


Pleurodonte josephinae nevisensis. Slopes of Nevis Peak, central Nevis, Lesser Antilles.


Pleurodonte perplexa. Grand Etang National Park, central Grenada, Lesser Antilles.

 


Pleurodontid snail, probably Pleurodonte sp. Colombier, Saint Bartholomew, Lesser Antilles.

(Photograph courtesy of Mr. Karl Questel).


Eurycratera jamaicensis. Windsor, north-central Jamaica.

 

Thelidomus aspera, juvenile and adults. Windsor, north-central Jamaica.


Family Sagdidae

 

    Members of the genus Sagda are particularly abundant in the islands of Jamaica. Related genera, like the monotypic Platysuccinea usually also inhabit very humid, forested areas.

 


Mating pair of sagdid snails, species undetermined. Windsor, north-central Jamaica.

 


Sagda grandis. Barbecue Bottom, north-central Jamaica.

 

Platysuccinea portoricensis, feeding on a fungus and active at night. El Yunque National Forest, north-eastern, Puerto Rico.

This species covers its shell in soil and debris, probably as a disguise.

The shell is fragile and semi-transparent, and the animal lives during the day under rotten logs or holes in tree trunks, and axils of leaves in rain forests.



A pair of Platysuccinea portoricensis prepare to mate.


Family Subulinidae

 

    These pulmonated snails are usually greatly elongated into thin, spiral cones. Most are small creatures found under rocks and debris. Some prey on smaller invertebrates and on the eggs of other animals like frogs.

 


Stenogyra terebraster, (family Subulinidae). Guilarte State Forest, west-central Puerto Rico.

 


Stenogyra sallei. Ebano Verde Scientific Reserve, central Dominican Republic, Hispaniola.

(Photograph courtesy of Dr. Jozef Grego).



Pseudobalea hasta. El Yunque National Forest, north-eastern Puerto Rico.



Pseudobalea sp. Florida, central Puerto Rico.

 

Family Urocoptidae

 

    This family is represented in the Caribbean islands snails like those of the genus Microceramus. They are commonly found in karstic zones or xeric areas. Most are small, and form part of the xerophilic gastropod fauna in such places.



Urocoptid snails, Macroceramus pontificus. Behind one of them is a Cerion striatella snail). Guanica State Forest, south-western Puerto Rico.


From Snails into Slugs

 

    Although evolution takes time and cannot be seen happening before one's eyes, the diverse stages of it can be seen as one compares snail that have ever smaller and "disfunctional" shells. Some of those species are shown below.

 

    These are almost always inhabitants of very humid environs. Some slugs do live in rather xeric areas, but will retreat and aestivate under rocks and debris during dry spells. In fact, the term "slug" has no systematic value and only refers to a specific morphology, as a number of them have evolved from different families of snails and are not closely related.

 

Snails with a reduced shell, Coloniconcha prima (family Pleurodontidae), adult and juvenile. Bahoruco Mountains, south-western Dominican Republic, Hispaniola.

 


With a proportionally even more reduced shell, the arboreal pleurodontid snail Parthena acutangula cannot retreat into it.

For that reason, it easily suffers from desiccation, and lives only in humid and rain forests.
This individual is feeding on leaves.

El Yunque National Forest, north-eastern Puerto Rico.

 


Juvenile and adult Gaeotis nigrolineata in water-conservation position. El Yunque National Forest, north-eastern Puerto Rico.

The transparent-green body of the amphibulimid snail is a good camouflage against its usual background of green leaves.

This is a snail with a vestigial, transparent shell. (The animal is almost a slug).
A denizen of the montane rain forests and cloud forests of the mountains of Puerto Rico, this species rests
during the day in the open, usually clinging to the underside of leaves to avoid sunlight.
The high atmospheric humidity of its habitat prevents its desiccation, even as it does not seek a moist shelter, as do many of its relatives without (and even with) a functional shell


ORDER SYSTELLOMMATOPHORA: LEATHERLEAF SLUGS

 

Family Veronicellidae

 

    These conspicuous and often big slugs can be seen crawling about at night. They do not possess lungs but nonetheless breathe air and are especially well adapted to moist tropical environments in the Antilles. Some species are quite large, and like their shelled relatives, live in humbid areas where they search for food at night.

 

Veronicella sloanei. Blue Mountains, east-central Jamaica.



Slug, possibly Veronicella portoricensis, El Yunque National Forest, north-eastern Puerto Rico.

Veronicellid slug, probably Veronicella sp. Blue Mountains, east-central Jamaica.