Octopus vulgaris
Domain: Eukarya
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Order: Octopoda
Family: Octopodidae
Genus: Octopus
Species: vulgaris
As both a member of the kingdom Animalia and the phylum Mollusca, Octopus vulgaris, also known as the common octopus, is both eukaryotic and multicellular. Also, the common octopus is a heterotroph, just like all members of animalia, groping through the ocean to find other animals to ingest [51]. One of the characteristics of Molluscs is that they have a nervous system “with a circum-oesophagal ring, ganglia and paired nerve chords” and O. vulgaris is no exception [52]. Additionally, like most animals and all molluscs, O. vulgaris is capable of relatively complex movement, using its eight arms, as well as jet propulsion, to swim. Moreover, O. vulgaris reproduces sexually, as do most animals and all molluscs [52]. Some other characteristics that put the common octopus into the phylum Mollusca are that it is symmetrical, has a complete gut including a mouth and anus, has an open circulatory system, uses gills for gas exchange, and has kidneys.
Octopus vulgaris usually is about 60 cm across, though its width can range between 30 cm and 1 meter [53], [54]. Its mantle is about 25 cm and its arms more than 1 meter, so that the total length of the common octopus can sometimes be more than 3 meters [51]. The head of O. vulgaris has two complex eyes with lenses and a mouth with jaws shaped similarly to a beak. Also, as suggested by the name octopus, O. vulgaris has 8 thick arms, each with two rows of suckers. They have no internal shell [53], [55]. The skin of the common octopus is smooth, and it can change color and surface structure based on the octopus’s mood and/or situation. Usually though, it is grayish yellow or brownish green [53], [55], [56].
The common octopus lives in tropical or semitropical climates in the Atlantic, Indian and Pacific Oceans, as well as the Mediterranean Sea; it is most common in the Mediterranean Sea, in the Eastern Atlantic Ocean, and off the coast of Japan. They can live in a few different conditions, including rocky, sandy and reef areas [51], [54], [56]. While they are normally found in waters between 25 and 50 meters deep, they can be found in water as shallow as 5 meters and as deep as 50 meters [51].
O. vulgaris is a predator of many molluscs and crustaceans including crabs, bivalves and gastropod [51]. They are able to identify their prey using various methods including movement, shape, scent and other features of the animals. They capture and eat them using one of several means. Firstly, O. vulgaris can use their arms to feel along the rocks for potential food. Another way that they can capture prey is by covering their prey with their web before leaping on it. Also, they can blast water at the ocean floor in an attempt to reveal food [51]. Once its prey is captured, the common octopus can kill its prey in a number of ways. An O. vulgaris has a structure with teeth called a radula that can be used to drill holes into the skull of Molluscs before inserting a toxin that incapacitates the animal [51], [53], [55]. Once it is done eating, the common octopus will leave pieces of the animal that they were eating around the entrance to its lair in a pile called a midden [53], [54].
O. vulgaris has two sexes (male and female). While they are usually solitary organisms, during mating season, a male octopus will insert a spermatophore sac into a female. At this time, the female will lay her fertilized eggs and stay and brood her eggs. O. vulgaris usually lives for 12 to 15 months, dying around the time the new generation is born [51].
Asterias rubens
Domain: Eukarya
Kingdom: Animalia
Subkingdom: Bilateria
Superphylum: Deuterostomia
Phylum: Echinodermata
Subphylum: Asterozoa
Class: Asteroidea
Superorder: Forcipulatacea
Order: Forcipulatida
Family: Asteriidae
Genus: Asterias
Species: rubens
Because it is a part of the kingdom Animalia, and more specifically, the phylum Echinodermata, Asterias rubens, more commonly known as the common starfish, is both eukaryotic and multicellular. Additionally, A. rubens is a heterotrophic, ingesting other animals, which fits the classification of the kingdom Animalia [57]. Like most animals, the common starfish has a nervous system. They do not have a brain, but they do have nerves that extend down each of their arms, which classifies them as Echinoderms [58]. A. rubens is also motile, which further classifies it under the kingdom Animalia. The common starfish is classified under Animalia because it can reproduce both sexually to produce offspring and asexually to regenerate, sometimes even entire limbs [59]. Furthermore, A. rubens has Pentamerous symmetry in adults and bilateral symmetry in larvae, a distinguishing characteristic in Echinoderms. They have a hard endoskeleton, a water vascular system that aids it in locomotion, feeding and respiration, a simple digestive system that includes a mouth, stomach, intestines and anus [59], [60].
The body of Asterias rubens has a central disk with arms radiating from it. While usually A. rubens has 5 arms, it can have as little as 4 or as many as 6 arms [57], [59]. Each arm can grow to be 26 cm, so the starfish can have a total diameter of about 52 cm. However, in shallow water, the common starfish will only grow to be about 15 cm across [59], [61]. Each arm is covered in a row of spines that runs along the center. A canal runs down the center of each arm with smaller branches coming off of it that connect to the tube feet. These tube feet have suckers at the end and are used for locomotion, respiration and eating. The radial canals are also connected to the circumoral canal, which is the main part of the common starfish’s water-vascular system. Additionally, A. rubens has an eye at the end of each arm that allows the starfish to perceive light [57], [59]. On the central disk, the common starfish has a mouth on its oral ventral side and an anus on its dorsal side [61]. A. rubens can range in color from red-orange to yellow-brown, and can sometimes even be violet [57], [59], [61].
Asterias rubens is most commonly found in the Northeast Atlantic Ocean, from the White Sea and Norway to Senegal [59]. In these temperate climates, the common starfish can withstand temperatures of up to 22 degrees Celsius. They can live in a wide range of depths, from sea level to 650 feet below that! A. rubens is usually found in fine sand, rock and gravel, mud flats, beds of mussels, and barnacles as these areas have a good source of nutrients for the starfish [57], [59].
A carnivorous species, A. rubens feeds on other animals including bivalves, gastropods and crabs. It uses its arms with its tube feet to hold onto its prey, then pulls the two halves of the shell apart. Once the inside of the shell is exposed, the common starfish extrudes its stomach from its mouth and gastric juices digest the food. Once the food is soft, it pulls the food back inside of its body [57], [59].
There are two separate sexes of A. rubens. Each starfish has ten gonads, two on each arm, which have pores that act as pathways for the sperm and eggs to exit the body for external fertilization. Fertilization acts as a chain reaction, with eggs from one starfish stimulating another starfish to drop its own eggs, which in turn stimulates the males to release their sperm [59]. The average common starfish will live between 5 and 10 years [57]. As mentioned earlier, A. rubens is also capable of asexual reproduction of its cells, regrowing up to four lost limbs.
Correlophus ciliatus
Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Gekkota
Family: Diplodactylidae
Genus: Correlophus
Species: ciliatus
Correlophus ciliatus, commonly known as the Crested Gecko, is a member of the kingdom Animalia and the phylum Chordata, and as such, is a multicellular eukaryote. Also, it is classified under the kingdom Animalia because of the way it eats; C. ciliatus is a heterotrophic, ingesting insects and plants, then digesting them. In fact, C. ciliatus has a full digestive system, placing it under the category of a Chordate. Also, like most animals, the Crested Gecko has a nervous sytem. Specifically, it has a brain and one major nerve chord that branches, which classifies it under the Phylum Chordata [62]. Also, the Crested Gecko has 4 legs, each with 4 fingers that allow them to move-- motility is a another characteristic of animals. Furthermore, the Crested Gecko reproduces both asexually within the cells of its body, as well as sexually, with the females laying eggs that are fertilized by the males [63]. Some other characteristics that C. ciliatus has that puts it under the classification of Chordata are: bilateral symmetry, segmented body, a tail, ventral heart and a closed circulatory system, and an endoskeleton [62].
The head of the Correlophus ciliatus is triangular and relatively large compared to its body. It has two big eyes and two big openings that function as ears at the side of its head. The body of the Crested Gecko is covered in granular scales that can range from light tan to reddish-brown in color. These scales are usually patterned with dark lateral stripes; Crested Geckos can be patternless, tiger or white-fringed. There are also calcareous crests along the back, above the eyes, and limbs, hence the name Crested Gecko [63]. The crests above the eyes help keep various particles out of the Gecko’s eyes as they do not have eyelids; however, the function of the other crests is not known. C. ciliatus also has four limbs with four fingers each and a prehensile tail which it uses to move. It has hairs on its fingers which allow it to cling to smooth or vertical surface, which is helpful for climbing trees. On average, the adult Crested Gecko has a total length of 20.3 cms and between 10.2-11.9 cm snout-to-vent length (SVL) [63].
Crested Geckos are found in the wild almost exclusively in the islands of Grand Terre and the Isle of Pines in New Caledonia. (However, there are unconfirmed sightings in Kotomo Island in New Caledonia.) These areas are are tropical rainforests with precipitation as high as 400 cm per year and average temperatures between 22.2 and 23.9 degrees Celsius. They are at elevations between 150 and 1,000 m above sea level. As nocturnal and arboreal animals, during the day they rest close to the ground where it is cooler. During the night, they move within the lower trees and shrubs, not climbing higher than 3 m off of the floor of the forest [63], [64].
Crested Geckos are omnivores, eating both insects and nectar and fruit. These foods have Calcium and Vitamin D3 which C. ciliatus needs for growth [63]. They have two sexes, though sex is not determined genetically; rather, environmental temperature when the egg is laid decides this. Higher temperatures cause a higher ratio of males to born whereas lower temperatures cause a higher ratio of females to be born. Thirty to forty days after a male and female copulate, the female will lay up to 4 eggs before copulating again. Within their ecosystem, Crested Geckos aid with distributing the pollen of various plants [63].
