Fish
The abundance of reef fish are limited by various factors, most importantly larval supply, space for shelter, food and predation. Nearly all reef fishes are site-attached throughout their benthic life cycle and only leave the reef for migration to feeding grounds or spawning aggregations. A journey across the ocean floor or to a neighbouring reef or most fish is highly dangerous. Coral reefs are vitally important to oceanic fish because they support an estimated 25% of marine life by providing nursery, spawning and refuge habitats as well as feeding areas.
There are so many fish in the ocean that it is impossible to document all. Here are a list of the common fish seen living on and around the sculptures They are grouped according to obvious anatomy or behaviour.
“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach
on “The Silent Evolution“
on the side of “The Dream Collector“
Oval and Thin Bodied Fish
Most fish in this category are colourful and have small pert mouths. Often the juvenile of a species is very different in appearance to the adult form.
Angelfish
Genus: Pterophyllum
Very attractive graceful swimmers with a round head and a long continuous dorsal and anal fin. Angelfish differ from butterfly fish by the well developed preopercular spine on their gill covers. Juvenile Angelfish are brightly marked, this signifies their behaviour as cleaners, removing parasites from other larger reef fish and therefore less likely to become prey. Adult fish largely feed on sponges and move from colony to colony of sponges but do never devour an entire sponge. They have evolved strong jaws with overlapping rows of teeth to eat the tough fibre of a sponge. Juveniles graze on algae and parasites. Some species live in harems and territory is fiercely protected by the group. Sometimes when the head male disappears, the largest female will change sex. The Grey and French Angel fish do not change sex and often live in a monogamous relationship with a similar sized partner for life. The Grey Angelfish is known to congregate in numbers of up to 20 as has been noticed over “The Silent Evolution” on several occasions .
Butterfly Fish
Family: Chaetodontidae
The Caribbean houses only seven of the 120 species of Butterfly fish. Generally of small size with concave heads and a protruding mouth housing teeth, makes them distinguishable to Angel fish. Normally a silver colour with yellow tint and dark strips which cover the eyes. They feed on small worms, hydroids or coral polyps, particularly Gorgonian coral, and swim in pairs. They use their dorsal spines to warn off predators and the false eye spot on juveniles and Foureye species assist to misdirect attacks.
Surgeonfish
Family: Acanthuridae
The name is derived from the sharp spines on the either side of their tail base, they are normally folded forward in a groove and cannot be voluntarily erected. The three species in this group are the Blue Tang, the Oceanic Surgeonfish and the Doctorfish. They are often found in mixed groups grazing on the algae on reefs. Doctorfish look very similar to Oceanic Surgeonfish however they have distinguishing body bars on either side. Both species can lighten or darken in colour dramatically. Blue Tangs have flat oval heads and are dark blue to purple in colour with white spine grooves at the tail base. The juvenile of the species has a bright yellow tail which slowly changes to blue as it matures. Their digestive system is anatomically alike to a herbivore but because most of the substrate of a reef contains hydroids and micro invertebrates which are inadvertently eaten, all three species are considered omnivores. Surgeon fish play a key role to the reef by grazing on algae therefore inhibiting the growth of turf algae and in the process they increase the amount of detritus to the habitat for other species.
Small Oval Bodied Fish
Damselfish
Family: Pomacentridae
The juvenile of these species are often brightly coloured while the adults are normally of dark colouration. They have very small mouths with fine teeth and feed on algae. They are very territorial and are known to nip at intruders. When their feeding area or egg nest is threatened they flare their fins and dart back and forth ready to attack. It is the males that fiercely defend the gametes during spawning. Blue Tangs have developed a way of penetrating the Damsel fish defences by swimming in groups. Most damselfish inhabit a single type of habitat and have a preference for substrate. They only ever co-exist with other species to share resources if there is a dominance relationship Eg. the Large Yellowtail Damselfish overlaps its feeding territory with the Dusky Damselfish however it is the Damselfish that is bullied into doing most of the protection.
Beaugregory
Species: Stegastes leucostictus
This is a type of carnivorous damselfish. As it does not need to defend algal patches, they typically inhabit calm shallow regions and often take refuge in empty conch shells and rubble. The juveniles are bright yellow with a demarcated blue dorsum while the adults are a dusky brown maintaining a pale to yellow tail.
Sergeant Major Fish
Abudefduf saxatilis are another type of Damselfish that have evolved to eat a broad diet and can live in different habitats. They eat algae, plankton, invertebrates, eggs off rocks and small fishes. Males defending the egg nests will turn a blue colour and will attack any intruder. The juveniles are miniature versions of the adults with yellow colouration and 5 vertical black bars to their bodies.
www.wetwebmedia.com/damsels.htm
“Reef fish behaviour” by Paul Humann, Ned DeLoach
“The Silent Evolution“
Siver Colouration
Barracuda
Genus: Sphyraena
These large piscavores have a primitive mouth with an under shot jaw lined with sharp teeth to severe fishes instantaneously. They spend most of their time swimming around the reef as opportunistic predators which are often outsmarted by their prey due to poor vision. They have webs of skin supported by a bony structure called ray fins instead of the fleshy type of fin. The Great Barracuda can reach up to 1.8 m long and has a prominent visible lateral line. Adults are solitary fish while juvenile will live in groups. Shiny rings and silver has been known to attract an attack as they resemble prey.
Bar Jack
Species: Carangoides ruber
Jacks are social animals normally swimming in schools throughout the open sea in search of food. They predate on small fish and crustaceans and often will congregate next to other predators like barracuda and stingrays. They have a distinguished black line running under the dorsal fin and onto the lower portion of the tail fin and can be fairly large up to 69cm long. Their jaws are pointed containing narrow bands of teeth and the upper has an outer row of re-curved teeth. They have been sighted in large groups on several occasions around “The Silent Evolution“.
Chub
Family: Ciprinidae
Rounded body with thin yellow/bronze horizontal stripes and a white linea streak below the eye from mouth to gill. Juveniles have light spots as large as an eye covering the body. The young reside amongst seagrass and weeds and the species live in shallow waters up to 30meters. Chubs are omnivores feeding on algae, small crustaceans and molluscs. They have been sighted cleaning parasites from themselves on the heel of “La Jardinera“
Other fish in this catagory include Palometa, Houndfish, White Mullet, Mojarras and Porgy’s.
species-identification.org/species.php?species_group=caribbean_diving_guide&id=191
www.thedivingblog.com/fish-identification-bar-jack/
“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach
Large Mouth and Tapered Bodied Fish with Notched Tails
Grunt
Family: Haemulidae
Grunts are named due to the ‘Grunt-like’ sound they make through their pharyngeal teeth and swim bladders. Populations can be numerous and dense around reefs, grass bed and sand flat habitats. Most Grunts have colourful stripes and very deeply notched tails and are similar to snappers but do not poses canine teeth. Grunts tend to be quite social and move around in large groups around reefs. They are bottom feeding predators, mostly at night on crustaceans. The juveniles resemble the adults in colour.
Snapper
Family: Lutjanidae
They gain their name due to the snapping action of their jaws when they are hooked. They have a continuous dorsal fin and a defined triangular head with a large mouth containing canine teeth. Large snapper can be solitary animals while the smaller species congregate in groups. The most common species are Grey Snappers, Yellow tail Snapper and Schoolmasters. Red snappers are deep water fish. Most snappers feed on shrimps, crabs, worms and smaller fish and some snappers especially the deep water group, can grow to a substantial size.
Tomtate
Species: Haemulon aurolineatum
These are a type of Grunt with a yellow stripe which runs from snout to tail and a dark spot near the tail base which may or may not be present.
Porkfish
Species: Anisotremus verginicus
The Porkfish is also a type of Grunt and are very graceful swimmers. They have a high back and brightly coloured yellow fins and head with two vertical stripes covering the eye and bordering the gills. They can be up to 40cm in length and are omnivores. They tend to swim in small schools and take refuge on reefs at night. They form a symbiotic relationship with other fish feeding on their parasites.
www.peteducation.com/article.cfm?c=16+1830&aid=1970
“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach
Other Fish
Parrotfish
Family: Scaridae
This group of fish have fused teeth forming a ‘beak’, large scales and primarily use their pectoral fins for locomotion. They use their mouths to scrape off algae and coral polyps consuming large quantities of calcium carbonate. They are quite often seen excreting a cloud of chalky waste. The juvenile parrotfish are very different in appearance to the brightly coloured adults. The adults emphasis their brightest colour during mating and courtship. Adults are solitary and are commonly sighted on reefs. In some species the largest fish change sex from female to male. Generally are less territorial than most reef fish due to the abundance of food they can eat. At night most parrotfish have a safe haven either in a rock crevice, cave or overhang or next to reef and one species the, Queen Parrotfish, will coat themselves in mucous to mask their scent while they are in a deep sleep or trance. The largest Parrot fish recorded is up to four feet in length.
Wrasse
Family: Labridae
Closely related to the Parrotfish but with protracted mouths, front canine teeth and smaller cigar shaped bodies. They use their teeth for eating crustaceans and other invertebrates like Brittlestars and Sea urchins. They tend to swim very busily around reefs in groups and some species are symbiotic or mutualistic, forming feeding stations for larger fish to cleanse themselves of parasites. Similar to Parrotfish they are often brightly coloured, change colour dependent on life stages and can change sex. This diverse family of fish range from the small Razorfish to the three foot long Hogfish. At night they take refuge in crevices or some species may burrow beneath sand.
Triggerfish
Family: Balistidae
Within the same family as Filefish, poses a long dorsal spine which can be voluntary raised and locked into place. They have a large head and small strong jaws with crushing teeth. Most feed on slow moving bottom dwellers like Sea urchins, crustaceans and molluscs while some species only feed on algae. They possess a thick skin overlaid by scales and notoriously can be quite aggressive.
Trunkfish
Family: Ostraciidae
A member of the Box Fish family and closely related to the Pufferfish, they are triangular in shape with a hexagonal pattern, small pert mouths and brush tails, used for escaping predators. They contain mucous secreting glands which release a toxin in defence. Trunkfish lack the sharp spine over each eye which Cowfish poses and the juveniles are brightly coloured. Normally they are very slow swimmers living in harems.
Rays
Family: Dasyatidae
Related to sharks , both being a species of cartilaginous fish. They have Flat disc shaped bodies with enlarged pectoral fins which are fused to their heads, with a ventrally positioned mouth. The protruding jaw works on a suspension mechanism with developed rounded teeth designed for eating crustaceans, molluscs and sometimes fish. Manta rays are mostly plankton eating creatures. Rays breath by moving water in through spiracles and not through their mouths. Rays obtained their name because they have the ability to release an electric shock when threatened. Stingrays, Electric rays and Guitarfish are bottom dwellers while Eagle rays are never resting on the sea bed and live in deeper water.
Flounders
Family: Bothidae
The Peacock Flounder is also known as the Flowery Flander due to blue flower -like marking along its dorsum. Their eyes are raised on stalks and can move independently and both are situated on top of the left side of their head providing a broad peripheral view. Adult Flounders swim sideways and therefore settle their body flat on the ground. They are normally found in shallow waters and can camoflague themselves against the substrate by releasing pigments to change the colour of their skin. If they feel threatened by predator Flounders can bury themselves into the sand leaving only their eyes protruding. They are omnivores generally on the hunt at night.
www.freshmarine.com/boxfish-trunkfish.html
“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach
animals.nationalgeographic.com/animals/fish/parrot-fish/
Bottom Dwellers
This group of fish consist of those living on rock, coral, sand or sponge surface. Here are just a few that have been spotted on the Sculptures. Others in this group include Jawfish, Flounders, Lizardfish and Frogfish.
Sea Horse
Genus: Hippocampus
Scorpion Fish
Seahorses are a bony fish without scales. They have a thin skin coating bony plates covering their entire body. The genus consist of almost 50 species and are found in sheltered shallow tropical and temperate seas. The number of rings on the body determines the species of fish and each individual is distinguished by a coronet on their head. Although closely related to the pipefish, seahorses are poor at swimming and in a vertical plane using their dorsal fin while their pectoral fins caudal to the eyes are used for direction. Some species form territories and live in a close ranging habitat while others, generally the females, will stray further. Sea horses camouflage to blend into the background substrate either seagrass, rock or coral reef, however in social or threatened moments they can become very brightly coloured. They use their long snouts to suck up plankton, shrimp, small fish and crustaceans. During reproduction a couple will carry out a courtship dance for several days before mating. The female deposits around 1,500 eggs into the males ‘brood pouch’ and it is his responsibility to carry the eggs until they are released into the ocean around one month later. The number of baby seahorses range from 100-200 depending on the species.
Seahorses are a species suffering from human damage. With depleting coral reefs and seagrass beds. They are also being used in Chinese medicine and their numbers are threatened.
Family: Scorpaenidae
This family of fish contain some of the most venomous species. They have spines which can sting and are coated with venomous mucous. Generally they have compressed stocky bodies, large heads and fleshy appendages for camouflage. They have spines on their heads, operculum and on their dorsal fins with venom glands. Most are bottom dwellers who feed on crustaceans and smaller fish. They camouflage themselves and wait for passing pray to ambush. They have large mouths with jaw teeth and using their gills they create a pressure vacuum to suck in unsuspecting prey.
Blenny
Suborder: Blennioidei
These are small fish with elongated bodies, large eyes and mouth and either burrow in crevices in reefs or spend most of their time on the sea floor. They have a long continuous dorsal fin and a rounded tail fin. They feed on algae and small benthic invertebrates. Five species can be found in the Caribbean and are brightly coloured and less than an inch in length. They can easily be confused with Gobies. Blennies have flexible bodies with appendages over their eyes and snouts called Cirri whereas Gobies have stiff bodies, two-part dorsal fins and no Cirri. Many have been seen living in small holes on some of the statues in Grenada and in Cancun however they are very difficult to find exposed for a photograph.
Goby
Family: Gobiidae
These are the smallest of this group of fish. They have a very straight posture with 2 dorsal fins. They can form symbiotic relationships with other species either acting as “watchmen” for shrimps or as “cleaners” to remove parasites from larger fish. We have seen many cleaning Gobies on Grace Reef however like Blenny’s they do not hang around for a photograph!
animals.nationalgeographic.com/animals/fish/sea-horse/
“Reef fish behaviour” by Paul Humann, Ned DeLoach
Crustaceans
Phylum: Arthropodia
Order: Decapods
These aquatic animals are invertebrates with a hard exoskeleton. They have two pairs of antennae and their bodies are divided into three parts; the head, thorax and abdomen. The fused head and thorax is covered by a carapace or dorsal shell. There order is derived from the five pairs of legs they have in which the front three pairs function as a mouth part. Most are scavengers.
Included in this group:
Lobsters: Lobsters are bottom dwellers with long cone-like antennae. In order to grow they have to go through a moulting stage which leaves them vulnerable to predation. They generally crawl along the surface floor but they can swim backwards by repeatedly curling their abdomen and using their wide flat tails if endangered. The presence of Hemocyanin in their blood makes it a blue colour. Lobsters are normally omnivores eating fish, small custaeceans, molluscs and plant matter. They prefer to live in self dug burrows however will take refuge in cracks and crevices. The clawed Lobsters are the ones known for culinary dishes however the Spiny and Slipper Lobsters lack large front claws
The sculptures “Anthropocene” and “La Jardinera” were designed with an internal tunnel system specifically for lobsters and shrimps to inhabit.
Crabs: Crabs make up nearly half of the 15,000 species within this order. They have evolved to have a reduced abdomen, four pairs of legs and a front pair of claws which are used for moving objects and for protection. Due to the articulations of their legs they move swiftly sideways along the surface floor and are generally very discrete and hard to locate. Crabs are often aggressive towards each other and communicate by waving or drumming their pinchers. They are omnivores and feed on algae, crustaceans, detritus and small molluscs.
Hermit Crabs: These are not true crabs, they have soft curved abdomens unlike most crustaceans. They use discarded shells as a home and when they outgrow one they move onto a larger one, often in gastropod shells.
Shrimps: Shrimps are Decapods with long legs, very thin antennae and its thin exoskeleton makes it lightweight for swimming. They tend to hide in dark recesses, within anemones or near sponge openings. Many species clean the area by feeding on bacteria residue and parasites from fish and a high tolerance to toxins. Examples in this group include: Coral banded shrimp (such as that living in the VW Beetle), Red snapping shrimp, Golden coral shrimp. They are distinguished from the true prawn by the differences in their gill structure.
Mantis Shrimp: These are not true shrimps and receive their name by resembling the praying mantis. They have very strong claws to capture prey an elongated body and feather-like gills on the lower abdomen. Typically they are aggressive and very fast predators that use their limbs as spears or smashing their prey. They are solitary animals that inhabit reefs and burrow in sand.
“Snorkelling guide to Marine Life” Paul Humann, Ned DeLoach
en.wikipedia.org/wiki/Decapoda
animals.nationalgeographic.com/animals/invertebrates/lobster/
www.bbc.co.uk/nature/blueplanet/factfiles/crustaceans/mantis_shrimp_bg.shtml
Echinoderms
Phylum: Echinodermata
These are ocean dwelling creatures which are found at every depth from shallow to the abyss. They have five body sections equally proportioned arranged around a central axis, this fivefold symmetry is called Pentermerism. Many move by adhesive tube feet which work to move the animal across the ocean floor and are vivid colours due to pigments the skin which can change colour with light intensities. They are important biologically to the reef system because they are so abundant and their ossified skeletons contribute to calcium carbonate formation.
Sea Stars or Star Fish
Class: Asteroidae
Most species have five arms with a central mouth located on the underneath surface with their anus dorsally forming pentaradial symmetry as an adult. When an arm is broken they can normally regenerate and occasional species have the ability to form a new animal from a severed member. Their bodies are composed of calcium carbonate ossicles or plates which form the endoskeleton and are externally expressed as spines or granules. Internally they have a hydraulic internal water-vascular system which is used for feeding and aid in its movement by projecting many tube feet along each arm for locomotion. They can live at a broad range of depth of water from intertidal to over 60,000 meters deep. They are opportunistic feeders, feeding on molluscs or sometimes coral and not all species are pure carnivores but can supplement their diet on algae and detritus. Some species have specialised feeding mechanisms such as suspension feeding and specific prey feeding. They have become known as a keystone species in ecology because they are very vulnerable to water pollution due to the simple gut and water vascular pump they posses. Sea stars can live up to 34 years.
The Silent Evolution Collection has become home to many Sea star families in a short space of time.
Brittle Stars
Class: Ophiuroidea
Similar in shape to a Sea star but with a small central axis containing all the internal organs and five slender arms containing several rows of spines. The mouth is a five toothed jaw system which serves as an anus as well as for ingestion. They move only laterally due to the formation of the calcareous plates along the dorsal surface of their arms and do not rely on their tube feet for locomotion. Severed arms can regenerate. They hide under rocks and in crevices but can be seen on sponges and soft corals.
Sea Urchins
Class: Echinoidea
Urchins are Spherical or globular creatures with long spines projecting from their bodies and tube feet and a mouth underneath usning the same water vascular system as sea stars. Their internal organs are enclosed in a hard shell composed of fused plates of calcium carbonate however the symmetry is not as obvious unless the shell is dried. The long spines can penetrate skin easily and are difficult to remove. They live off algae and organic food which they scrape off of rocks using a mouth with a five tooth arrangement. Common colours range from Black to dull green, brown and red and can differ in size from 6-36cm. They are closely related to the Sand Dollar and their roe is a delicacy is some cuisines. The West Indian Sea Egg a large example of an urchin which devours algae and often found under the camouflage of snails and in crabs.
Heart Urchins: Oval dome shaped urchins distinguished by a mouth and anus at different ends of the body forming a “heart” shape. Their bodies are covered with closely arranged short spines adapted for burrowing under the sand or mud. They feed on organic material underneath the ocean substrate by extending long tentacles.
Sea Cucumbers
Class: Holothuroidea
Sea cucumbers have elongated rounded bodies which obscure the five segment separation. They have a mouth and an anus at opposite ends of the body. Their endoskeletal ossicles are buried beneath a leathery skin and body wall. Some species have very reduced or absent tube feet. A variety of fish, worms and crabs have developed a symbiotic relationship with sea cucumbers by living under their anus for protection. Sea cucumbers contain both a water vascular system and haemal system making them more complex to the rest of the phylum. They crawl very slowly along the surface and communicate by sending hormone signals through the water. They are scavengers gathering up plankton and organic debris
“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach
www.britannica.com/EBchecked/topic/258504/heart-urchin
animals.nationalgeographic.com/animals/invertebrates/starfish/
en.wikipedia.org/wiki/Echinoderm
Segmented Worms
Phylum: Annelida
Oceanic worms or annelids, can be hard to distinguish disguised against the reef or they are easily seen like the free moving.
Fireworms: Their long segmented bodies are divided externally by ring-like constrictions called annuli and internally by septa. Most segments contain the same sets of organs although they share a common gut, nervous system and circulatory system. Most annelids have a closed circulatory system and the blood is circulated entirely in blood vessels. The body is covered by a cuticle make form strong flexible collagen that is secreted by the skin beneath. They bury their bodies below rock or coral attached to the reef and the visible section are called “radioles” which are featherlike projections. These radioles function as gills for oxygen and waste exchange and also as a method for capturing prey, plankton in the water. Marine worms count for over one third of bottom dwelling animals around reefs and in the tidal zones. The burrowing species increase the penetration of oxygen and water into the sea bed and therefore in turn encourage the growth of bacteria and small animals alongside their habitat.
Beared Fireworm: These flattened segmented worms are very colourful and can reach up to 35cm in length. Each body segment has a pair of lobe-like pedicles called ‘parapodia’ which are used for swimming, burrowing and feeding. They have a group of poisonous white bristles on either side of their body which are extended if threatened. The neurotoxin they release can easily penetrate skin through the bristles and cause intense irritation. They are found living on reefs or rocky habitats and can be seen up to 150 meters below the surface. Fireworms are voracious predators on hard and soft corals, anemones and small crustaceans.
Christmas Tree Worm: Tube building worms with twin spíral plumes of tenticles forming a Serpulid shaped like a Christmas tree, used for feeding and respiration. They retract their plumes into the burrow in coral when disturbed. Typically they are relatively small , 3.6cm, come in a variety of bright colours and white and are sedentary worms living on plankton in the water.
Feather Duster: Normally live in colonies all with the same characteristics. The small worm lives inside the central tube with a single circular ring of radioles protruding. The radioles act like gills for gas exchange and also trap tiny particles in the water. These animals live in the reef where there us a current and can be found in depths of 5-50m.
Star Horseshoe Worm: Another variety of Tube worm with a double fold of radioles forming a U-shaped crown. The entry into the tube as a small covering made from calcareous discs. Most are shades of red, brown, orange and white. The entire animal is around 10cm and the crown protrudes about 4cm. They are very common in the Caribbean and are found at depth up to 30m.
“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach
Stocky Cerith Snail, Cerithium litteratum on “The Silent Evoluion”
MOLLUSCS
Phylum: Mollusca
The largest invertebrate marine phylum group with about 85,000 identified species. They vary greatly across the phylum with size, habitat, behaviour and anatomy. Universal anatomical parts of molluscs are a mantle; which secretes calcium carbonate, proteins and chitin to form the ‘shell’ to cover the upper part of the body, and the nervous system made of 2 pairs of nerve cords or three pairs in bivalve molluscs. The mantle contains a large void used for breathing and excretion. Underneath the animal contains one large muscular foot for locomotion using a coating of mucus. The circulatory system of molluscs is mainly open in which fluid called ‘haemolymph’ fills a cavity ‘haemocoel’ and bathes the organs. One organ can be used for various functions E.g. the heart and kidney play. The fluid movement is aided by locomotion. The feed using a strong tongue with a rasping action and digest food using micro hairs or ‘cilia’ and mucus. Most are herbivores and their staple diet is algae.
CEPHALOPODS: Contain Squids, Cuttlefish and Octopus. This group have the most advanced nervous system in the Mollusca phyllum. The squid is the largest invertebrate, The Colossal Squid can reach up to 10m in length. This group are predatory animals using jaws and tentacles to acquire food as apposed to its tongue like the other classes of molluscs. Squids have eight arms and 2 long tentacles at the rear end of their body. They are social creatures and live in groups. Octopuses have eight arms with suction caps and a flaccid globular shaped body. They live on the ocean floor and move using their arms. When threatened Octopuses can force out a jet of dark ink and swiftly move backwards by expelling a rapid jet of water from the mantle cavity. Cuttlefish have eight arms and two tentacles with suckers which grasp their prey. They have the largest brain to body ratio to all invertebrates.
GASTROPODAS: Contain Snails and Slugs. This group are the most abundant, averaging at 80% of mollusc species recorded. Snails form cone shaped shells which continue to enlarge as the body grows and acts as protection. Their movement is generally slow. Conch is a common name for a group of shells with a high spire and a siphonal canal, they are commonly recognised in the ocean and are used by humans for food, pink pearls and the shell is an instrument or even art. The Stocky Cerith as found on “The Silent Evolution” are a hardy algae eating snail and can be seen in large numbers while food is available. Sea slugs do not have a shell and are completely covered dorsally by a colourful undulating mantle.
BIVALVIA: Contain Clams, Oysters, Scallops, Muscles. These are soft-bodied animals with two shells ‘valves’ protecting the body. The two halves are held together by a ligament forming a ‘hinge’ which can open the shells for feeding and respiration. Bivalvia evolved to filter feeding and therefore do not have a tongue but have developed a siphon to take in and expel water. Their gills are very developed to capture food particles in the water. They vary greatly in shape and size from 0.52mm to The Giant Clam that can weigh up to 200kg. Due to a sedentary lifestyle they have very simple nervous systems and do not have a brain like other molluscs. Scallops are the only bivalve with developed eyes while the others have very simple light sensitive cells. They contain several sense receptors for taste and motion and tentacle with taste receptor cells.
SCAPHOPODIA: Tusk Shells meaning “shovel footed” range from 0.5-15cm in length and have a sub-tidal habitat residing off shore or within the sea bed substrate. They feed on detritus.
“Snorkelling Guide to Marine Life” by Paul Humann, Ned DeLoach